Highly efficient influenza matrix (m1) proteins

ABSTRACT

This invention discloses a method of increasing production of virus-like particles comprising expressing an avian influenza matrix protein. The invention also comprises methods of making and using said VLPs.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application under 37 C.F.R. §1.53(b) of pending U.S. Non-Provisional patent application Ser. No. 12/832,657, filed Jul. 8, 2010, which is a continuation application of U.S. Non-Provisional patent application Ser. No. 12/558,844, filed Sep. 14, 2009, which claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/096,561, filed Sep. 12, 2008. U.S. Non-Provisional patent application Ser. No. 12/558,844 also claims priority under 35 U.S.C. §120 as a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 12/340,186, filed Dec. 19, 2008, which claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/015,440, filed Dec. 20, 2007. U.S. Non-Provisional patent application Ser. No. 12/558,844 also claims priority under 35 U.S.C. §120 as a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 11/582,540, filed Oct. 18, 2006, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. Nos. 60/727,513, filed Oct. 18, 2005, 60/780,847, filed Mar. 10, 2006, 60/800,006, filed May 15, 2006, 60/831,196, filed Jul. 17, 2006, 60/832,116, filed Jul. 21, 2006, and 60/845,495, filed Sep. 19, 2006, and also claims priority under 35 U.S.C. §120 as a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 10/617,569, filed Jul. 11, 2003; this application is also related to U.S. Non-Provisional patent application Ser. No. 11/372,466, filed Mar. 10, 2006, and International Patent Application Serial No. PCT/US2004/022001, filed Jul. 9, 2004, all of which are incorporated herein by reference in their entireties for all purposes.

GOVERNMENT RIGHTS STATEMENT

A portion of this invention was made with government support under contract RFA-AI-03-016 awarded by the Department of Health and Human Services. The government has certain rights in the invention.

DESCRIPTION OF THE TEXT FILE SUBMITTED ELECTRONICALLY

The contents of the text file submitted electronically herewith are incorporated herein by reference in their entirety: A computer readable format copy of the Sequence Listing (filename: NOVV_(—)039_(—)03US_SeqList_ST25.txt, date recorded: Feb. 22, 2011, file size 197 kilobytes).

BACKGROUND OF INVENTION

Influenza virus is a member of Orthomyxoviridae family (for review, see Murphy and Webster, 1996). There are three subtypes of influenza viruses designated A, B, and C. The influenza virion contains a segmented negative-sense RNA genome. The influenza virion includes the following proteins: hemagglutinin (HA), neuraminidase (NA), matrix (M1), proton ion-channel protein (M2), nucleoprotein (NP), polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2), polymerase acidic protein (PA), and nonstructural protein 2 (NS2) proteins. The HA, NA, M1, and M2 are membrane associated, whereas NP, PB1, PB2, PA, and NS2 are nucleocapsid associated proteins. The NS1 is the only nonstructural protein not associated with virion particles but specific for influenza-infected cells. The M1 protein is the most abundant protein in influenza particles. The HA and NA proteins are envelope glycoproteins, responsible for virus attachment and penetration of the viral particles into the cell, and the sources of the major immunodominant epitopes for virus neutralization and protective immunity. Both HA and NA proteins are considered the most important components for prophylactic influenza vaccines because they are highly immunogenic.

Influenza virus infection is initiated by the attachment of the virion surface HA protein to a sialic acid-containing cellular receptor (glycoproteins and glycolipids). The NA protein mediates processing of the sialic acid receptor, and virus penetration into the cell depends on HA-dependent receptor-mediated endocytosis. In the acidic confines of internalized endosomes containing an influenza virion, the HA protein undergoes conformational changes that lead to fusion of viral and host cell membranes followed by virus uncoating and M2-mediated release of M1 proteins from nucleocapsid-associated ribonucleoproteins (RNPs), which migrate into the cell nucleus for viral RNA synthesis. Antibodies to HA molecule can prevent virus infection by neutralizing virus infectivity, whereas antibodies to NA proteins mediate their effect on the early steps of viral replication.

To date, all commercially available influenza vaccines for non-pandemic strains in the United States have been propagated in embryonated hen's eggs. Although influenza virus grows well in hen's eggs, production of vaccine is dependent on the availability of eggs. Supplies of eggs must be organized, and strains for vaccine production selected months in advance of the next flu season, limiting the flexibility of this approach, and often resulting in delays and shortages in production and distribution. Unfortunately, some influenza vaccine strains, do not replicate well in embryonated chicken eggs, and have to be isolated by cell culture in a costly and time consuming procedure.

Systems for producing influenza viruses in cell culture have also been developed in recent years (See, e.g., Furminger. Vaccine Production, in Nicholson et al. (eds) Textbook of Influenza pp. 324-332; Merten et al. (1996) Production of influenza virus in cell cultures for vaccine preparation, in Cohen & Shafferman (eds) Novel Strategies in Design and Production of Vaccines pp. 141-151). Typically, these methods involve the infection of suitable immortalized host cells with a selected strain of virus. While eliminating many of the difficulties related to vaccine production in hen's eggs, not all pathogenic strains of influenza grow well and can be produced according to established tissue culture methods. In addition, many strains with desirable characteristics, e.g., attenuation, temperature sensitivity and cold adaptation, suitable for production of live attenuated vaccines, have not been successfully grown in tissue culture using established methods. In addition, live attenuated viruses have not been accepted by the general public due to fears reversion to a virulent virus.

Inactivated influenza A and B virus vaccines are licensed currently as trivalent vaccines for parenteral administration. These trivalent vaccines are produced as monovalent bulk in the allantoic cavity of embryonated chick eggs, purified by rate zonal centrifugation or column chromatography, inactivated with formalin or β-propiolactone, and formulated as a blend of the two strains of type A and the type B strain of influenza viruses in circulation among the human population for a given year. The available commercial influenza vaccines are whole virus (WV) or subvirion (SV; split or purified surface antigen) virus vaccines. The WV vaccine contains intact, inactivated virions. SV vaccines treated with solvents such as tri-n-butyl phosphate (Flu-Shield, Wyeth-Lederle) contain nearly all of the viral structural proteins and some of the viral envelopes. SV vaccines solubilized with Triton X-100 (Fluzone, Sanofi-Aventis; Fluvirin, Novartis) contain aggregates of HA monomers, NA, and NP principally, although residual amounts of other viral structural proteins are present. A live attenuated cold-adapted virus vaccine (FluMist, MedImmune) was granted marketing approval recently by the FDA for commercial usage as an intranasally delivered vaccine indicated for active immunization and the prevention of disease caused by influenza A and B viruses in healthy children and adolescents, 5-17 years of age and healthy adults 18-49 years of age.

Several recombinant products have been developed as recombinant influenza vaccine candidates. These approaches have focused on the expression, production, and purification of influenza virus type A HA and NA proteins, including expression of these proteins using baculovirus infected insect cells (Crawford et al, 1999; Johansson, 1999; Treanor et al., 1996), viral vectors (Pushko et al., 1997; Berglund et al., 1999), and DNA vaccine constructs (Olsen et al., 1997).

Crawford et al. (1999) demonstrated that influenza HA expressed in baculovirus infected insect cells is capable of preventing lethal influenza disease caused by avian H5 and H7 influenza subtypes. At the same time, another group demonstrated that baculovirus-expressed influenza HA and NA proteins induce immune responses in animals superior to those induced by a conventional vaccine (Johansson et al., 1999) Immunogenicity and efficacy of baculovirus-expressed hemagglutinin of equine influenza virus was compared to a homologous DNA vaccine candidate (Olsen et al., 1997). Taken together, the data demonstrated that a high degree of protection against influenza virus challenge can be induced with recombinant HA or NA proteins, using various experimental approaches and in different animal models.

Lakey et al. (1996) showed that a baculovirus-derived influenza HA vaccine was well-tolerated and immunogenic in human volunteers in a Phase I dose escalation safety study. However, results from Phase II studies conducted at several clinical sites in human volunteers vaccinated with several doses of influenza vaccines comprised of HA and/or NA proteins indicated that the recombinant subunit protein vaccines did not elicit protective immunity [G. Smith, Protein Sciences; M. Perdue, USDA, Personal Communications]. These results indicated that conformational epitopes displayed on the surface of HA and NA peplomers of infectious virions were important in the elicitation of neutralizing antibodies and protective immunity.

Regarding the inclusion of other influenza proteins in recombinant influenza vaccine candidates, a number of studies have been carried out, including the experiments involving influenza nucleoprotein, NP, alone or in combination with M1 protein (Ulmer et al., 1993; Ulmer et al., 1998; Zhou et al., 1995; Tsui et al., 1998). These vaccine candidates, which were composed of quasi-invariant inner virion proteins, elicited a broad spectrum immunity that was primarily cellular (both CD4+ and CD8+ memory T cells). These experiments involved the use of the DNA or viral genetic vectors. Relatively large amounts of injected DNA were needed, as results from experiments with lower doses of DNA indicated little or no protection (Chen et al., 1998). Hence, further preclinical and clinical research may be required to evaluate whether such DNA-based approaches involving influenza NP and M1 are safe, effective, and persistent.

Recently, in an attempt to develop more effective vaccines for influenza, particulate proteins were used as carriers of influenza M2 protein epitopes. The rationale for development of an M2-based vaccine was that in animal studies protective immunity against influenza was elicited by M2 proteins (Slepushkin et al., 1995). Neirynck et al. (1999) used a 23-aa long M2 transmembrane domain as an amino terminal fusion partner with the hepatitis B virus core antigen (HBcAg) to expose the M2 epitope(s) on the surface of HBcAg capsid-like particles. However, in spite of the fact that both full-length M2 protein and M2-HBcAg VLP induced detectable antibodies and protection in mice, it was unlikely that future influenza vaccines would be based exclusively on the M2 protein, as the M2 protein was present at low copy number per virion, was weakly antigenic, was unable to elicit antibodies that bound free influenza virions, and was unable to block virus attachment to cell receptors (i.e. virus neutralization).

Since previous research has shown that the surface influenza glycoproteins, HA and NA, are the primary targets for elicitation of protective immunity against influenza virus and that M1 provides a conserved target for cellular immunity to influenza, a new vaccine candidate may include these viral antigens as a protein macromolecular particle, such as virus-like particles (VLPs). Further, the particle with these influenza antigens may display conformational epitopes that elicit neutralizing antibodies to multiple strains of influenza viruses.

Virus-like particles mimic the overall structure of a virus particle without the requirement of containing infectious material. VLPs lack a viral DNA or RNA genome, but retain the three-dimensional structure of an authentic virus. VLPs have the ability to stimulate B-cell mediated responses, CD4 proliferative responses and cytotoxic T lymphocytes responses (see, Schirmbeck et al. (1996) Eur. J. Immunol., 26, 2812-2822). In addition, virus-like particles induce MHC class I-restricted T-cell responses.

Several studies have demonstrated that recombinant influenza proteins could self-assemble into VLPs in cell culture using mammalian expression plasmids or baculovirus vectors (Gomez-Puertas et al., 1999; Neumann et al., 2000; Latham and Galarza, 2001). Gomez-Puertas et al. (1999) demonstrated that efficient formation of influenza VLP depends on the expression levels of viral proteins. Neumann et al. (2000) established a mammalian expression plasmid-based system for generating infectious influenza virus-like particles entirely from cloned cDNAs. Latham and Galarza (2001) reported the formation of influenza VLPs in insect cells infected with recombinant baculovirus co-expressing human influenza virus HA, NA, M1, and M2 genes. These studies demonstrated that influenza virion proteins may self-assemble upon co-expression in eukaryotic cells.

However, one problem associated with the use of the M1 protein from human strains of influenza virus is that they are poor proteins for efficient VLP formation. Indeed, the present inventors have found that the use of the M1 protein from human seasonal strains results in low quantities of VLPs that are not sufficient for commercial VLP production. Suprisingly, the present inventors found that M1 proteins derived from avian strains of influenza virus are much more favorable proteins for efficient VLP production. This increased efficiency was found to be mediated in part by a single amino acid difference in the M1 protein (an R to K substitution at position 101 of the M1 protein). This mutation was found almost exclusively in avian M1 proteins. Importantly, the present inventors have found that in order to produce recoverable levels of VLPs sufficient for vaccine production, it is necessary to use M1 proteins, such as avian M1 proteins, harboring the K¹⁰¹ amino acid residue. Accordingly, the knowledge that increased formation and recovery of VLPs using M1 proteins containing this amino acid substitution is critical to vaccine development.

SUMMARY OF INVENTION

In a first aspect, the present invention provides virus-like particles (VLPs) comprising an influenza M1 protein comprising a K¹⁰¹ residue. In one embodiment, the M1 protein comprises the amino acid residues YKKL (SEQ ID NO: 61) at the amino acids corresponding to positions 100-103 of the protein encoded by SEQ ID NO: 3. In another embodiment, the M1 protein comprises the amino acid residues YKKL at the positions corresponding to positions 100-103 of SEQ ID NO: 49. In another embodiment, the M1 protein is derived from an avian influenza virus strain. In an exemplary embodiment, the avian influenza virus strain is A/Indonesia/5/05.

In various embodiments described herein, the VLPs of the invention may further comprise influenza hemagglutinin (HA) and/or neuraminidase (NA) proteins. In one embodiment, the HA and NA proteins are derived from an avian influenza virus. In one embodiment, the avian influenza virus is H5N1. In another embodiment, the avian influenza virus in H9N2.

In another embodiment, the VLPs of the invention may further comprise HA and/or NA proteins derived from a non-avian influenza virus. In one embodiment, the non-avian influenza protein is a seasonal influenza protein. In one embodiment, the seasonal influenza virus is a type A influenza virus. In another embodiment, the seasonal influenza virus is a type B influenza virus.

In various embodiments described herein, the HA and/or NA may exhibit hemagglutinin and/or neuraminidase activity, respectively.

In additional embodiments, the HA and/or NA may be chimeric proteins. In one embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic terminal domains of avian or heterologous influenza HA and/or NA. In an exemplary embodiment, the non-avian influenza HA and/or NA are derived from the influenza strain A/Wisconsin/67/2005 and the avian influenza HA and/or NA are derived from influenza strain A/Indonesia/5/05.

In a second aspect, the present invention provides a method of increasing the efficiency of influenza VLP production comprising expressing an influenza M1 protein comprising a K¹⁰¹ residue and at least one non-avian influenza protein in a host cell. In one embodiment, the M1 protein comprises the amino acid residues YKKL (SEQ ID NO: 61) at the amino acids corresponding to positions 100-103 of the protein encoded by SEQ ID NO: 3. In another embodiment, the M1 protein comprises the amino acid residues YKKL at the positions corresponding to positions 100-103 of SEQ ID NO: 49. In another embodiment, the M1 protein is derived from an avian influenza virus strain. In an exemplary embodiment, the avian influenza virus strain is A/Indonesia/5/05. In one embodiment, said non-avian influenza protein is a seasonal influenza protein. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of avian or heterologous influenza HA and/or NA.

The present invention also comprises a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, the VLP further comprises HA and/or NA proteins derived from a non-avian influenza virus. In one embodiment, the non-avian influenza protein is a seasonal influenza protein. In various embodiments described herein, the HA and/or NA have hemagglutinin and/or neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of avian or heterologous influenza HA and/or NA. In another embodiment, said non-avian influenza protein is from an infectious agent. In another embodiment, said infectious agent is a virus, bacterium, fungus, or parasite. In another embodiment, said non-avian influenza protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and or influenza NA fused to a protein, or a portion thereof, from an infective agent. In another embodiment, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said infectious agent comprises at least one SARS virus protein. In another embodiment, said SARS virus protein is the S protein. In another embodiment, said S protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and or influenza NA fused to the S protein. In another embodiment, said avian influenza M1 protein comprises a lysine at the second position of the M1 protein L domain. In another embodiment, said L domain comprises the sequence YKKL. In another embodiment, said VLP is expressed from a eukaryotic cell comprising one or more nucleic acids encoding an influenza M1 protein under conditions that permit the formation of VLPs. In another embodiment, said eukaryotic cell is selected from the group consisting of yeast, inset, amphibian, avian and mammalian cells. In another embodiment, said insect cell is Sf9.

The present invention also provides VLPs comprising an influenza M1 protein comprising a lysine at the second position of the M1 protein L domain (e.g. K¹⁰¹). In one embodiment, said L domain comprises the sequence YKKL. In another embodiment, the M1 protein exhibits increased VLP formation efficiency as compared to an M1 protein comprising an arginine at the second position of the M1 protein L domain. In another embodiment, the increased VLP formation efficiency is at least a 50% increase in VLP formation with substantially equivalent amounts of M1 protein expression. In another embodiment, the VLP formation efficiency is measured by comparing M1 protein levels in a VLP fraction. In another embodiment, the VLP further comprises an influenza HA and/or NA protein. In another embodiment, the HA and/or NA protein is from an avian, pandemic, and/or seasonal influenza virus. In another embodiment, the VLP further comprises a heterologous protein. In another embodiment, said VLP is expressed from a eukaryotic cell comprising one or more nucleic acids encoding an influenza M1 protein under conditions that permit the formation of VLPs. In another embodiment, said eukaryotic cell is selected from the group consisting of yeast, inset, amphibian, avian and mammalian cells. In another embodiment, said insect cell is Sf9.

The present invention also comprises an antigenic formulation comprising a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP comprises HA and/or NA from a non-avian influenza virus. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian or heterologous influenza HA and/or NA. In another embodiment, the antigenic formulation comprises a chimeric VLP comprising an influenza M1 protein comprising an lysine at the second position of the M1 protein L domain. In another embodiment, said L domain comprises the sequence YKKL. In another embodiment, said non-avian influenza protein is from an infectious agent. In another embodiment, said infectious agent is from a virus, bacteria, fungus and/or parasite. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent. In another embodiment, said non-avian influenza protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and or influenza NA fused to a protein, or a portion thereof, from an infective agent. In another embodiment, said VLPs comprise more than one protein from an infectious agent.

The present invention also comprises vaccines comprising a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP comprises HA and/or NA from a non-avian influenza virus. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian or heterologous influenza HA and/or NA. In another embodiment, the antigenic formulation comprises a chimeric VLP comprising an influenza M1 protein comprising an lysine at the second position of the M1 protein L domain. In another embodiment, said L domain comprises the sequence YKKL. In another embodiment, said non-avian influenza protein is derived from an infectious agent. In another embodiment, the infectious agent is a virus, bacterium, fungus or parasite. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with a protein, or a portion thereof, from an infectious agent. In another embodiment, said non-avian influenza protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein, or a portion thereof, from an infectious agent. In another embodiment, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said VLP is formulated with an adjuvant or immune stimulator. In another embodiment, said adjuvant comprises Novasomes®.

The present invention also comprises a method of inducing immunity in a vertebrate comprising administering to said vertebrate a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said immune response is a humoral immune response. In another embodiment, said immune response is a cellular immune response. In another embodiment, said method comprises administering to said vertebrate the vaccine orally, intradermally, intranasally, intramuscularly, intraperitoneally, intravenously, or subcutaneously. In another embodiment, at least two effective doses of the vaccine are administered. In another embodiment, said doses are administered at least 2 weeks apart, at least 3 weeks apart, at least 4 weeks apart, at least 5 weeks apart or at least 6 weeks apart.

The present invention also comprises a method of preventing and/or reducing a viral infection or symptom thereof, comprising administering to a vertebrate a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein.

The present invention also comprises a method of reducing the severity of influenza in a population, comprising administering the a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein to enough individuals in said population in order to prevent or decrease the chance influenza virus transmission to another individual in said population.

The invention also provides for a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the vaccine formulations of the invention. In one embodiment, the vaccine formulations of the invention are packaged in a hermetically sealed container such as an ampoule or sachette indicating the quantity of composition.

The present invention provides for a vaccine comprising an influenza VLP, wherein said VLP comprises influenza M1, HA and NA proteins, wherein said vaccine induces substantial immunity to influenza virus infection in an animal susceptible to influenza. In one embodiment, said M1 protein is derived from a different influenza virus strain as compared to the HA and NA proteins. In another embodiment, said HA and/or NA exhibit hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said influenza VLP comprises seasonal influenza virus HA and NA proteins. In another embodiment, said influenza VLP comprises avian influenza HA and NA proteins. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

The present invention also provides for a method of inducing substantial immunity to influenza virus infection in an animal susceptible to influenza, comprising administering at least one effective dose of the vaccine comprising an influenza VLP. In one embodiment, said method comprises administering to an animal said influenza VLP orally, intradermally, intranasally, intramusclarly, intraperitoneally, intravenously, or subcutaneously.

The present invention also provides for a method of formulating a vaccine that induces substantial immunity to influenza virus infection to an animal susceptible to influenza, comprising adding to said formulation an effective dose of an influenza VLP, wherein said VLP comprises influenza M1, HA and NA proteins, wherein said vaccine induces substantial immunity to influenza virus infection to said animal. In one embodiment, said VLP consists essentially of influenza M1, HA and NA proteins. In another embodiment, said VLP consists of influenza M1, HA and NA proteins. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

The present invention also provides for a virus like particle (VLP) comprising an influenza virus M1 protein and influenza virus H5 and N1 hemagglutinin and neuraminidase proteins. In one embodiment said M1 protein is derived from a different influenza virus strain as compared to the H5 and N1 proteins. In one embodiment, said H5 or N1 are from a H5N1 clade 1 influenza virus. In another embodiment, said H5 and N1 are from a H5N1 clade 2 influenza virus.

The invention also provides a macromolecular protein structure containing (a) a first influenza virus M1 protein and (b) an additional structural protein, which may include a second or more influenza virus M1 protein; a first, second or more influenza virus HA protein; a first, second, or more influenza virus NA protein; and a first, second, or more influenza virus M2 protein. If the additional structural protein is not from a second or more influenza virus M1 protein, then both or all members of the group, e.g., first and second influenza M2 virus proteins are included. As such, there is provided a functional influenza protein structure, including a subviral particle, VLP, or capsomer structure, or a portion thereof, a vaccine, a multivalent vaccine, and mixtures thereof consisting essentially of influenza virus structural proteins produced by the method of the invention. In a particularly preferred embodiment, the influenza macromolecular protein structure includes influenza virus HA, NA, and M1 proteins that are the expression products of influenza virus genes cloned as synthetic fragments from a wild type virus. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

The macromolecular protein structure may also include an additional structural protein, for example, a nucleoprotein (NP), membrane proteins from species other than noninfluenza viruses and a membrane protein from a non-influenza source, which are derived from avian or mammalian origins and different subtypes of influenza virus, including subtype A and B influenza viruses. The invention may include a chimeric macromolecular protein structure, which includes a portion of at least one protein having a moiety not produced by influenza virus.

Prevention of influenza may be accomplished by providing a macromolecular protein structure that may be self-assembled in a host cell from a recombinant construct. The macromolecular protein structure of the invention has the ability to self-assemble into homotypic or heterotypic virus-like particles (VLPs) that display conformational epitopes on HA and NA proteins, which elicit neutralizing antibodies that are protective. The composition may be a vaccine composition, which also contains a carrier or diluent and/or an adjuvant. The functional influenza VLPs elicit neutralizing antibodies against one or more strains or types of influenza virus depending on whether the functional influenza VLPs contain HA and/or NA proteins from one or more viral strains or types. The vaccine may include influenza virus proteins that are wild type influenza virus proteins. Preferably, the structural proteins containing the influenza VLP, or a portion of thereof, may be derived from the various strains of wild type influenza viruses. The influenza vaccines may be administered to humans or animals to elicit protective immunity against one or more strains or types of influenza virus.

The macromolecular protein structures of the invention may exhibit hemagglutinin activity and/or neuraminidase activity.

The invention provides a method for producing a VLP derived from influenza by constructing a recombinant construct that encodes influenza structural genes, including M1, HA, and at least one structural protein derived from influenza virus. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein. A recombinant construct is used to transfect, infect, or transform a suitable host cell with the recombinant baculovirus. The host cell is cultured under conditions which permit the expression of M1, HA and at least one structural protein derived from influenza virus and the VLP is formed in the host cell. The infected cell media containing a functional influenza VLP is harvested and the VLP is purified. The invention also features an additional step of co-transfecting, co-infecting or co-transforming the host cell with a second recombinant construct which encodes a second influenza protein, thereby incorporating the second influenza protein within the VLP. Such structural proteins may be derived from influenza virus, including NA, M2, and NP, and at least one structural protein is derived from avian or mammalian origins. The structural protein may be a subtype A and B influenza viruses. According to the invention, the host cell may be a eukaryotic cell. In addition, the VLP may be a chimeric VLP.

The invention also features a method of formulating a drug substance containing an influenza VLP by introducing recombinant constructs encoding influenza viral genes into host cells and allowing self-assembly of the recombinant influenza viral proteins into a functional homotypic or heterotypic VLP in cells. The influenza VLP is isolated and purified and a drug substance is formulated containing the influenza VLP. The drug substance may further include an adjuvant. In addition, the invention provides a method for formulating a drug product, by mixing such a drug substance containing an influenza VLP with a lipid vesicle, i.e., a non-ionic lipid vesicle. Thus, functional homotypic or heterotypic VLPs may bud as enveloped particles from the infected cells. The budded influenza VLPs may be isolated and purified by ultracentrifugation or column chromatography as drug substances and formulated alone or with adjuvants such as Novasomes®, a product of Novavax, Inc., as drug products such as vaccines. Novasomes®, which provide an enhanced immunological effect, are further described in U.S. Pat. No. 4,911,928, which is incorporated herein by reference.

The invention provides a method for detecting humoral immunity to influenza virus infection in a vertebrate by providing a test reagent including an effective antibody-detecting amount of influenza virus protein having at least one conformational epitope of an influenza virus macromolecular structure. The test reagent is contacted with a sample of bodily fluid from a vertebrate to be examined for influenza virus infection. Influenza virus specific antibodies contained in the sample are allowed to bind to the conformational epitope of an influenza virus macromolecular structure to form antigen-antibody complexes. The complexes are separated from unbound complexes and contacted with a detectably labeled immunoglobulin-binding agent. The amount of the detectably labeled immunoglobulin-binding agent that is bound to the complexes is determined.

Influenza virus may be detected in a specimen from an animal or human suspected of being infected with the virus by providing antibodies, which have a detectable signal producing label, or are attached to a detectably labeled reagent, having specificity to at least one conformational epitope of the particle of the influenza virus. The specimen is contacted with antibodies and the antibodies are allowed to bind to the influenza virus. The presence of influenza virus in the specimen is determined by means of the detectable label.

The invention provides methods for treatment, prevention, and generating a protective immune response by administering to a vertebrate an effective amount of the composition of the invention.

Alternatively, the influenza VLP drug substance may be formulated as laboratory reagents used for influenza virus structure studies and clinical diagnostic assays. The invention also provides a kit for treating influenza virus by administering an effective amount of a composition of the invention and directions for use.

The invention also provides for a VLP comprising HA, NA and M1 proteins derived from a virus which can cause morbidity or mortality in a vertebrate. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein. In one embodiment, said HA, NA and M1 proteins are derived from an avian influenza type A virus. In another embodiment the HA is selected from the group consisting of H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 and H16 and the NA is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In a further embodiment, said HA and NA proteins are H5 and N1, respectively. In another embodiment, said HA and NA proteins are H9 and N2, respectively. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In one embodiment, the VLP consists essentially of HA, NA and M1 proteins, i.e., these are substantially the only influenza proteins in the VLP.

The invention also provides for a method of producing a VLP, comprising transfecting vectors encoding avian influenza virus proteins into a suitable host cell and expressing said avian influenza virus proteins under condition that allow VLPs to be formed. In one embodiment, this method involves transfecting a host cell with recombinant DNA molecules that encode only the HA, NA and M1 influenza proteins. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

The invention also comprises an antigenic formulation comprising a VLP comprising HA, NA and M1 proteins derived from a virus which can cause morbidity or mortality in a vertebrate. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein. In another embodiment, the HA is selected from the group consisting of H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 and H16 and the NA is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In a further embodiment, said HA and NA proteins are H5 and N1, respectively. In another embodiment, said HA and NA proteins are H9 and N2, respectively. In a further embodiment, said antigenic formulation is administered to the subject orally, intradermally, intranasally, intramusclarly, intraperitoneally, intravenously, or subcutaneously.

The invention further provides for a method of vaccinating a vertebrate against avian influenza virus comprising administering to said vertebrate a protection-inducing amount of a VLP comprising HA, NA and M1 proteins derived from an avian influenza virus. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

This invention also comprises a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP. In one embodiment, said VLP consists essentially of HA, NA and M1. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein. In another embodiment, said VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully.

This invention also comprises a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP. In one embodiment, said influenza VLP consists essentially of HA, NA and M1. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

This invention further comprises a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of a influenza VLP. In one embodiment, said influenza VLP consists essentially of HA, NA and M1. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In a further embodiment, the influenza M1 protein is an avian influenza M1 protein.

This invention further comprises a method of inducing a substantially protective antibody response to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP.

This invention comprises a method of inducing a substantially protective cellular immune response to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP.

This invention further comprises a method of formulating a vaccine that induces substantial immunity to influenza virus infection or at least one symptom thereof to a subject, comprising adding to said formulation an effective dose of an influenza VLP. In one embodiment, said substantial immunity to influenza virus infection or at least one symptom thereof is delivered in one dose. In another embodiment, said substantial immunity to influenza virus infection or at least one symptom thereof is delivered in multiple doses.

This invention further comprises a vaccine comprising an influenza VLP, wherein said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof when administered to a subject. In one embodiment, said influenza VLP is an avian influenza VLP. In another embodiment, said influenza VLP is a seasonal influenza VLP.

This invention further comprises an antigenic formulation comprising an influenza VLP, wherein said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof when administered to a subject. In one embodiment, said influenza VLP is an avian influenza VLP. In another embodiment, said influenza VLP is a seasonal influenza VLP.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the nucleotide sequence of avian influenza A/Hong Kong/1073/99 (H9N2) virus neuraminidase (NA) gene (SEQ ID NO:1).

FIG. 2 depicts the nucleotide sequence of avian influenza A/Hong Kong/1073/99 (H9N2) virus hemagglutinin (HA) gene (SEQ ID NO:2).

FIG. 3 depicts the nucleotide sequence of avian influenza A/Hong Kong/1073/99 (H9N2) virus matrix protein M1 (M1) gene (SEQ ID NO:3).

FIG. 4 depicts the transfer vectors for construction of recombinant baculoviruses for expression of avian influenza A/Hong Kong/1073/99 (H9N2) HA, NA, and M1 proteins. FIG. 4A depicts a transfer vector for expression of individual genes and FIG. 4B depicts the transfer vector for multi-expression of the genes.

FIG. 5 depicts the expression of avian influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 proteins in Sf-95 cells.

FIG. 6 depicts the purification of avian influenza A/Hong Kong/1073/99 (H9N2) VLPs by the sucrose density gradient method.

FIG. 7 depicts the detection of influenza virus protein by gel filtration chromatography. The antibodies used in the Western blot analyses are as follows: (A) rabbit anti-H9N2; (b) murine anti-M1 mAb; and (C) murine anti-BACgp64.

FIG. 8 depicts the detection of avian influenza A/Hong Kong/1073/99 (H9N2) proteins including subviral particles, VLP, and VLP complexes, by electron microscopy.

FIG. 9 depicts the hemagglutination activity of purified avian influenza A/Hong Kong/1073/99 (H9N2) VLPs.

FIG. 10 depicts the neuraminidase activity of purified avian influenza A/Hong Kong/1073/99 (H9N2) VLPs.

FIG. 11 depicts the immunization and bleed schedule for the immunogenicity study of recombinant influenza with purified avian influenza A/Hong Kong/1073/99 (H9N2) VLPs in mice.

FIG. 12 depicts the results of an immunogenicity study in mice immunized with recombinant influenza H9N2 VLPs. FIG. 12A depicts sera from BALB/c mice immunized with recombinant VLPs comprised of HA, NA, and M1 proteins from avian influenza virus type A/H9N2/Hong Kong/1073/99. FIG. 12B depicts sera from New Zealand white rabbits immunized with inactivated avian influenza virus type A H9N2 were reacted with Western blots containing inactivated avian influenza virus type A H9N2 (lanes 1 and 3) or cold-adapted avian influenza virus type A H9N2 (lanes 2 and 4).

FIG. 13 depicts the geometric mean antibody responses in BALB/c mice after a primary and secondary immunization.

FIG. 14 depicts serum hemagglutinin inhibition (HI) responses in BALB/c mice.

FIG. 15 depicts weight loss (%) in BALB/c mice challenged with H9N2 influenza.

FIG. 16 depicts lung virus titers at 3 and 5 days post challenge with H9N2.

FIGS. 17A, 17B and 17C depict mice antibody response to A/Fujian/411/2002 when immunized with H3N2 VLP.

FIGS. 18 A and B depict mice IgG antibody isotypes

FIG. 19 hemagglutinin inhibition (HI) antibody responses in SD Rats immunized with H9N2 VLP vaccine.

FIGS. 20A and 20B depict hemagglutinin inhibition (HI) antibody responses to different doses of H9N2 VLPs with and without adjuvant in BALB/c mice.

FIG. 21 depicts serum hemagglutinin inhibition (HI) responses in BALB/c mice between different doses of VLPs.

FIG. 22 depicts serum hemagglutinin inhibition (HI) responses in ferrets.

FIG. 23 depicts serum hemagglutinin inhibition (HI) responses from serum pulled on days 21 and 42 from ferrets after administration of different strains of H3N2 VLPs.

FIG. 24 depicts anti-HA Antibody (Endpoint Dilution Titer) of mice inoculated intramuscularly with H5N1 (Vietnam/1203/2003) VLPs at low doses.

FIG. 25 depicts anti-HA Antibody (Endpoint Dilution Titer) of mice inoculated intranasally with H5N1 (Vietnam/1203/2003) VLPs at low doses.

FIG. 26 depicts an example for manufacturing, isolating and purifying VLPs of the invention.

FIG. 27 depicts mice inoculated with H3N2 VLPs given intramuscularly and subsequently challenged intranasally with A/Aichi/2/68x31 (H3N2) virus.

FIG. 28 depicts mice inoculated with H3N2 VLPs given intranasally and subsequently challenged intranasally with A/Aichi/2/68x31 (H3N2) virus.

FIG. 29 depicts virus shedding in nasal washes of ferret inoculated with H9N2 VLP vaccine and subsequently challenged intranasally with H9N2 virus.

FIG. 30A, 30B, 30C, 30D, 30E, 30F, 30G, 30H depicts hemagglutinin inhibition (HI) antibody responses in mice after inoculation with different doses of A/Fujian/411/2002 (H3N2) VLPs intramuscularly or intranasally tested against different H3N2 strains of influenza viruses.

FIG. 31 depicts a stained SDS-PAGE gel derived from VLPs made from different constructs after isolation from a sucrose gradient.

FIG. 32 depicts a stained western blot derived from VLPs made from different constructs after isolation from a sucrose gradient.

FIG. 33 is a stained SDS-PAGE gel derived from VLPs made from wild type or hybrids of A/Indonesia/5/05 M1 and A/Fujian/411/2002 HA and NA.

FIG. 34 depicts a stained western blot derived from VLPs made from wild type or hybrids of A/Indonesia/5/05 M1 and A/Fujian/411/2002 HA and NA.

FIG. 35 depicts the amino acids sequence of SARS S protein with Indonesia H5N1 HA transmembrane and carboxyl terminal domain (underlined) (SEQ ID NO: 62).

FIG. 36 depicts the amino acids sequence of Indonesia H5N1 M1 protein.

FIG. 37 depicts pFastBac 1 vector containing coding sequences for SARS S with Indonesia H5N1 HA TM/CT domain and Indonesia H5N1 M1 protein.

FIG. 38 depicts the purified SARS S/Indo M1 chimeric VLPs. Lane 1 is coomassie blue stain. Lane 2 is western blot, top panel: anti SARS S; bottom panel: anti influenza M1.

FIG. 39 depicts purified wild type SARS VLPs composed of SARS S, M and E proteins. A) Coomassie blue stain; B) Western blot, top panel: anti SARS S; bottom panel: anti SARS M.

FIG. 40 depicts particle size analysis result for SARS S/Indo M1 chimeric VLPs with Malvern Zetasizer.

FIG. 41A-C depicts electron microscope (EM) negative stain of SARS S/Indo M1 chimeric VLPs. A) EM image for buffer control; B) Selected EM images for VLPs; C) Selected EM images for VLPs at higher magnitude.

FIG. 42 A-C depicts Published EM images for SARS-CoV and coronavirus.

FIG. 43 depicts expression constructs for production of B/Florida/4/06 VLPs in Sf9 insect cells. Shown are the location of HA, NA, and M1 genes, as well as locations of polyhedron promoter. Also shown are the constructs for individual expression of HA and NA genes for reagent purposes.

FIG. 44 depicts expression levels of influenza B/Florida/4/06 VLPs by Coomassie staining (left panel) and HA/NA assays (right panel). Lane 1. Sample of B/Florida/4/06 VLPs containing B/Florida/4/06 M1, Lane 2. Sample of B/Florida/4/06 VLPs containing B/Ann Arbor/1/1986 M1, Lane 3 Sample of B/Florida/4/06 VLPs containing A/Indonesia/5/05 (H5N1) M1. The right panels shows HA and NA activity by the hemagglutination and neuraminidase enzyme activity essays.

FIG. 45 depicts Electron microscopy of purified VLPs. Negative staining transmission electron microscopy of influenza B/Florida/4/06 VLPs containing M1 from A/Indonesia/5/05 (H5N1) (left), B/Ann Arbor/1/1986 (middle), and B/Florida/4/06 (right).

FIG. 46 depicts the M1 amino acid sequences of three avian influenza strains and a variety of seasonal and pandemic human influenza strains.

FIG. 47 depicts the amino acid changes in seven A/Fujian mutants generated by site-directed mutagenesis.

FIG. 48 depicts a SDS-PAGE gel derived from the expression of Influenza Fujian M1 Mutants. The left panel is stained for total proteins with Coomassie blue, the right panel is stained for influenza M protein by western blot.

FIG. 49 depicts a SDS-PAGE gel derived from VLPs made from Influenza Fujian M1 Mutants. The left panel is stained for total proteins with Coomassie blue, the right panel is stained for influenza M protein by western blot.

FIG. 50 depicts recombinant baculovirus (rBV) constructs for expression of native, reassortant, and M1-deficient VLPs in Sf9 cells. Influenza HA, NA, and M1 genes were generated for each indicated strain by RT-PCR using extracted viral RNA. Additionally, the M1 Indo, M1 PR/8, and M1 AA/1 genes for A/Indonesia/5/05 (H5N1), A/PR/8/34 (H1N1), B/Ann Arbor/1/66, respectively, were used in reassortant VLPs. The HA, NA, and M1 genes were combined within each rBV in a tandem fashion so that each gene was expressed from its own expression cassette that included polyhedrin promoter (PolH) and SV40 polyadenylation signal (pA).

FIG. 51 depicts expression of influenza proteins in the native, reassortant and M1-deficient VLPs, by coomassie staining and western blot. Sf9 cells were infected with rBVs (FIG. 50) for 72 hr, and VLPs were concentrated and partially purified from culture media by ultracentrifugation at 10 000×g for 1 hr through a 30% sucrose cushion. Pellets were resuspended in PBS. Lanes 1-4, A/Brisbane/59/07 (H1N1) VLPs generated using rBVs 526, 599, 587, and 590, respectively (FIG. 50); lanes 5-8, A/Brisbane/10/07 (H3N2) VLPs generated using rBVs 528, 520, 521, and 547, respectively (FIG. 50); lanes 9-12, B/Florida/4/06 VLPs generated using rBVs 540, 538, 539, and 601, respectively (FIG. 50). M, Precision Plus protein molecular weight marker (Bio-Rad, Hercules, Calif.). Locations of influenza proteins are indicated on the left. Western blots were done using sheep antisera raised against H1N1, H3N2, and influenza B viruses, followed by alkaline phosphatase-conjugated anti-sheep IgG (H+L) (Kirkegaard and Perry, Gaithersburg, Md.). Also shown is expression of M1 proteins in the infected Sf9 cells (bottom panel) by western blot using the same antisera.

FIG. 52 depicts purified H3N1 VLPs, by coomassie staining (A) and transmission electron microscopy (B). Lane 1 (A), panel 1 (B), native VLPs containing M1 derived from A/Brisbane/10/07 (H3N2) and generated in Sf9 cells infected with rBV 528 (FIG. 50). Lane 2 (A), panel 2 (B), reassortant VLPs containing M1 derived from A/Indonesia.5/05 (H5N1) and generated using rBV 520. Lane 3 (A), panel 3 (B), reassortant VLPs containing M1 derived from A/PR/8/34 (H1N1) and generated using rBV 521. Lane 4 (A), panel 4 (B), M1-deficient VLPs generated using rBV 547 (FIG. 50). Protein molecular weights and location of influenza proteins are indicated. For electron microscopy, VLPs were stained with 1% phosphotungstic acid. Direct magnification 120 000×. Bar, 100 nm.

FIG. 53 depicts the effect of the K¹⁰¹ residue on expression of M1-only VLPs. (A) Mutagenesis of residues R¹⁰¹, S²⁰⁷, S²²⁴; and T²²⁷ of A/Fujian/411/02 M1 protein to K¹⁰¹, N²⁰⁷, N²²⁴, or A²²⁷ of A/Indonesia/5/05 M1 protein. Expression of M1 in infected Sf9 cells (lanes 1-7) and media (lanes 8-14), by coomassie staining and western blot using antibody to M1. Lanes 1, 8, T²²⁷A; lanes 2, 9, double mutant S²²⁴N, T²²⁷A; lanes 3, 10, R¹⁰¹K; lanes 4, 11, S²⁰⁷N; lanes 5, 12, S²²⁴N; lanes 6, 13, triple mutant S²⁰⁷N, S²²⁴N, T²²⁷A; lanes 7, 14, quadruple mutant R¹⁰¹K, S²⁰⁷N; S²²⁴N; T²²⁷A. (B) Mutagenesis of M1 from A/Indonesia/5/05 and A/Udorn/72. Expression of M1 proteins in infected Sf9 cells (lanes 1-4) and media (lanes 5-8), by coomassie staining and western blot using antibody to M1. Lanes 1, 5, wild type M1 protein derived from A/Indonesia/5/05 (H5N1); lanes 2, 6, mutant M1-R¹⁰¹ protein derived from A/Indonesia/5/05 (H5N1); lanes 3, 7, wild type M1 protein derived from A/Udorn/72 (H3N2); lanes 4, 8, mutant M1-K¹⁰¹ protein derived from A/Udorn/72 (H3N2).

FIG. 54 depicts the 3-D structure of M1 and alignment of residues within the α-helix 6. (A) Three-dimensional structure of two M1 monomers, as seen on Cn3D image of PDB ID 1EA3 determined by X-ray crystallography (Arzt et al., 2001). The location of R/K¹⁰¹ residue within α-helix 6 is highlighted in yellow. (B) Alignment of M1 protein fragment 91-105 containing K¹⁰¹ residue.

FIG. 55 depicts Effect of engineered K¹⁰¹ residue within M1 on expression of H3N2 VLPs. (A) Constructs for expression of influenza A/Fujian/411/02 (H3N2) VLPs. The constructs include a tandem for co-expression of HA and NA genes, as well as the wild type and mutant M1 containing R¹⁰¹ and K¹⁰¹, respectively. As a control, M1 derived from A/Indonesia/5/05 (H5N1) containing K¹⁰¹ was used. (B) Expression of M1 alone and within VLPs in the infected Sf9 cells (lanes 1-6) and medium (lanes 7-12), by coomassie staining and western blot. Lanes 1, 7, wild type M1-K101 protein derived from A/Indonesia/5/05 (H5N1); lanes 2, 8, wild type R¹⁰¹ protein derived from A/Fujian/411/02 (H3N2); mutant M1-K¹⁰¹ protein derived from A/Fujian/411/02 (H3N2).

DETAILED DESCRIPTION OF THE INVENTION Definitions:

As used herein, the term “baculovius,” also known as baculoviridae, refers to a family of enveloped DNA viruses of arthropods, members of which may be used as expression vectors for producing recombinant proteins in insert cell cultures. The virion contains one or more rod-shaped nucleocapsids containing a molecule of circular supercoiled double-stranded DNA (Mr 54×10⁶-154×10⁶). The virus used as a vector is generally Autographa californica nuclear polyhedrosis virus (NVP). Expression of introduced genes is under the control of the strong promoter that normally regulates expression of the polyhedron protein component of the large nuclear inclusion in which the viruses are embedded in the infected cells.

As used herein, the term “derived from” refers to the origin or source, and may include naturally occurring, recombinant, unpurified, or purified molecules. The proteins and molecules of the present invention may be derived from influenza or non-influenza molecules.

As used herein, the term “chimeric protein” refers a constructs that links at least two heterologous proteins into a single macromolecule (fusion protein).

As used herein, the term “chimeric VLP” refers to a virus-like particle that comprises an M1 protein derived from a first source and at least one protein, or portion thereof, that is not derived from said first source.

As used herein the term “first” influenza virus protein, i.e., a first influenza virus M1 protein, refers to a protein, such as M1, HA, NA, and M2, that is derived from a particular strain of influenza virus. The strain or type of the first influenza virus differs from the strain or type of the second influenza virus protein. Thus, “second” influenza virus protein, i.e., the second influenza virus M1 protein, refers to a protein, such as M1, HA, NA, and M2, that is derived from a second strain of influenza virus, which is a different strain or type than the first influenza virus protein.

As used herein, the term “hemagglutinin activity” refers to the ability of HA-containing proteins, VLPs, or portions thereof to bind and agglutinate red blood cells (erythrocytes).

As used herein, the term “neuraminidase activity” refers to the enzymatic activity of NA-containing proteins, VLPs, or portions thereof to cleave sialic acid residues from substrates including proteins such as fetuin.

As used herein, the term “heterotypic” refers to one or more different types or strains of virus.

As used herein, the term “homotypic” refers to one type or strain of virus.

As used herein, the term “macromolecular protein structure” refers to the construction or arrangement of one or more proteins.

As used herein, the term “multivalent” vaccine refers to a vaccine against multiple types or strains of influenza virus.

As used herein, the term “non-influenza” refers to a protein or molecule that is not derived from influenza virus.

As used herein, the term “vaccine” refers to a preparation of dead or weakened pathogens, or of derived antigenic determinants, that is used to induce formation of antibodies or immunity against the pathogen. A vaccine is given to provide immunity to the disease, for example, influenza, which is caused by influenza viruses. The present invention provides vaccine compositions that are immunogenic and provide protection. In addition, the term “vaccine” also refers to a suspension or solution of an immunogen (e.g. VLP) that is administered to a vertebrate to produce protective immunity, i.e., immunity that reduces the severity of disease associated with infection.

As used herein the term “substantial immunity” refers to an immune response in which when VLPs of the invention are administered to a vertebrate there is an induction of the immune system in said vertebrate which results in the prevention of influenza infection, amelioration of influenza infection or reduction of at least one symptom related to influenza virus infection in said vertebrate. Substantial immunity may also refer to a haemagglutination inhibition (HI) titer of ≧40 in a mammal wherein the VLPs of the invention have been administered and have induced an immune response.

As used herein the term “adjuvant” refers to a compound that, when used in combination with a specific immunogen (e.g. a VLP) in a formulation, augments or otherwise alters or modifies the resultant immune response. Modification of the immune response includes intensification or broadening the specificity of either or both antibody and cellular immune responses. Modification of the immune response can also mean decreasing or suppressing certain antigen-specific immune responses.

As used herein the term “immune stimulator” refers to a compound that enhances an immune response via the body's own chemical messengers (cytokines). These molecules comprise various cytokines, lymphokines and chemokines with immunostimulatory, immunopotentiating, and pro-inflammatory activities, such as interleukins (e.g., IL-1, IL-2, IL-3, IL-4, IL-12, IL-13); growth factors (e.g., granulocyte-macrophage (GM)-colony stimulating factor (CSF)); and other immunostimulatory molecules, such as macrophage inflammatory factor, Flt3 ligand, B7.1; B7.2, etc. The immune stimulator molecules can be administered in the same formulation as the influenza VLPs, or can be administered separately. Either the protein or an expression vector encoding the protein can be administered to produce an immunostimulatory effect.

As used herein an “effective dose” generally refers to that amount of the VLP of the invention sufficient to induce immunity, to prevent and/or ameliorate influenza virus infection or to reduce at least one symptom of influenza infection and/or to enhance the efficacy of another dose of a VLP. An effective dose may refer to the amount of the VLP sufficient to delay or minimize the onset of an influenza infection. An effective dose may also refer to the amount of the VLP that provides a therapeutic benefit in the treatment or management of influenza infection. Further, an effective dose is the amount with respect to the VLPs of the invention alone, or in combination with other therapies, that provides a therapeutic benefit in the treatment or management of an influenza viral infection. An effective dose may also be the amount sufficient to enhance a subject's (e.g., a human's) own immune response against a subsequent exposure to influenza virus. Levels of immunity can be monitored, e.g., by measuring amounts of neutralizing secretory and/or serum antibodies, e.g., by plaque neutralization, complement fixation, enzyme-linked immunosorbent, or microneutralization assay. In the case of a vaccine, an “effective dose” is one that prevents disease or reduces the severity of symptoms.

As used herein, the term “external domain” when referring to membrane associated proteins refer to the domain(s) of the protein that are external to the cell and/or cytosol and/or a lumen. The external domain of a protein is also known as an ectodomain.

As used herein the term “avian influenza virus” refers to influenza viruses found chiefly in birds but that can also infect humans or other animals. In some instances, avian influenza viruses may be transmitted or spread from one human to another. An avian influenza virus that infects humans has the potential to cause an influenza pandemic, i.e., morbidity and/or mortality in humans. A pandemic occurs when a new strain of influenza virus (a virus in which human have no natural immunity) emerges, spreading beyond individual localities, possibly around the globe, and infecting many humans at once.

As used herein the term “non-avian influenza protein” refers to a protein that is heterologous to an avian influenza virus. Said non-avian influenza protein may be recombinantly expressed from an expression vector and may be heterologous to the expression vector.

As used herein the term “seasonal influenza virus” refers to the influenza viral strains that have been determined to be passing within the human population for a given influenza season based on epidemiological surveys conducted by National Influenza Centers worldwide. These epidemiological studies, and some isolated influenza viruses, are sent to one of four World Health Organization (WHO) reference laboratories, one of which is at the Centers for Disease Control and Prevention (CDC) in Atlanta for detailed testing. These laboratories test how well antibodies made to the current vaccine react to the circulating virus and new flu viruses. This information, along with information about flu activity, is summarized and presented to an advisory committee of the U.S. Food and Drug Administration (FDA) and at a WHO meeting. These meetings result in the selection of three viruses (two subtypes of influenza A viruses and one influenza B virus) to go into flu vaccines for the following fall and winter. The selection occurs in February for the northern hemisphere and in September for the southern hemisphere. Usually, one or two of the three virus strains in the vaccine changes each year.

As used herein, the term “influenza VLP” refers to a VLP comprising at least one influenza protein. Said VLPs can comprise additional influenza and/or non-influenza proteins.

As use herein, the term “infectious agent” refers to microorganisms that cause an infection in a vertebrate. Usually, the organisms are viruses, bacteria, parasites and/or fungi. The term also refers to different antigenic variations of the same infectious agent.

As used herein the term “substantially protective antibody response” refers to an immune response mediated by antibodies against an influenza virus, which is exhibited by a vertebrate (e.g., a human), that prevents or ameliorates influenza infection or reduces at least one symptom thereof. VLPs of the invention can stimulate the production of antibodies that, for example, neutralizing antibodies that block influenza viruses from entering cells, blocks replication of said influenza virus by binding to the virus, and/or protect host cells from infection and destruction.

As used herein the term “substantially protective cellular response” refers to an immune response that is mediated by T-lymphocytes and/or other white blood cells against influenza virus, exhibited by a vertebrate (e.g., a human), that prevents or ameliorates influenza infection or reduces at least one symptom thereof. One important aspect of cellular immunity involves an antigen-specific response by cytolytic T-cells (“CTL”s). CTLs have specificity for peptide antigens that are presented in association with proteins encoded by the major histocompatibility complex (MHC) and expressed on the surfaces of cells. CTLs help induce and promote the destruction of intracellular microbes, or the lysis of cells infected with such microbes. Another aspect of cellular immunity involves an antigen-specific response by helper T-cells. Helper T-cells act to help stimulate the function, and focus the activity of, nonspecific effector cells against cells displaying peptide antigens in association with MHC molecules on their surface. A “cellular immune response” also refers to the production of cytokines, chemokines and other such molecules produced by activated T-cells and/or other white blood cells, including those derived from CD4+ and CD8+ T-cells.

As used herein the term “immunity” refers to induction of the immune system of a vertebrate wherein said induction results in the prevention, amelioration, and/or reduction of at least one symptom of an infection in said vertebrate Immunity may also refer to a hemagglutination inhibition (HI) titer of ≧40 when VLPs of the invention have been administered to a vertebrate and said VLPs have induced an immune response against a HA of an influenza virus.

As used herein the term “substantial immunity in a population-wide basis” refers to immunity as a result of VLPs of the invention administered to individuals in a population. The immunity in said individual in said population results in the prevention, amelioration of influenza infection, or reduction of at least one symptom related to influenza virus infection in said individual, and prevents the spread of said influenza virus to others in the population. The term population is defined as group of individuals (e.g. schoolchildren, elderly, healthy individuals etc.) and may comprise a geographic area (e.g. specific cities, schools, neighborhoods, workplace, country, state, etc.).

As use herein, the term “antigenic formulation” or “antigenic composition” refers to a preparation which, when administered to a vertebrate, especially a bird or a mammal, will induce an immune response.

As use herein, the term “vertebrate” or “subject” or “patient” refers to any member of the subphylum cordata, including, without limitation, humans and other primates, including non-human primates such as chimpanzees and other apes and monkey species. Farm animals such as cattle, sheep, pigs, goats and horses; domestic mammals such as dogs and cats; laboratory animals including rodents such as mice, rats and guinea pigs; birds, including domestic, wild and game birds such as chickens, turkeys and other gallinaceous birds, ducks, geese, and the like are also non-limiting examples. The terms “mammals” and “animals” are included in this definition. Both adult and newborn individuals are intended to be covered.

As used herein, the term “virus-like particle” (VLP) refers to a structure that in at least one attribute resembles a virus but which has not been demonstrated to be infectious. Virus-like particle in accordance with the invention do not carry genetic information encoding for the proteins of virus-like particles. In general, virus-like particles lack a viral genome and, therefore, are noninfectious. In addition, virus-like particles can often be produced in large quantities by heterologous expression and can be easily purified.

Influenza Virus Vaccines

Influenza remains a pervasive public health concern despite the availability of specific inactivated virus vaccines that are 60-80% effective under optimal conditions. When these vaccines are effective, illness is usually averted by preventing viral infection. Vaccine failure can occur as a result of accumulated antigenic differences (antigenic shift and antigenic drift). For example, avian influenza virus type A H9N2 co-circulated with human influenza virus type A Sydney/97 (H3N2) in pigs and led to genetic reassortment and emergence of new strains of human influenza virus with pandemic potential (Peiris et al., 2001). In the event of such antigenic shift, it is unlikely that current vaccines would provide adequate protection.

Another reason for the paucity of influenza vaccine programs is the relatively short persistence of immunity elicited by the current vaccines. Further inadequacy of influenza control measures reflects restricted use of current vaccines because of vaccine reactogenicity and side effects in young children, elderly, and people with allergies to components of eggs, which are used in manufacturing of commercially licensed inactivated virus influenza vaccines.

Additionally, inactivated influenza virus vaccines often lack or contain altered HA and NA conformational epitopes, which elicit neutralizing antibodies and play a major role in protection against disease. Thus, inactivated viral vaccines, as well as some recombinant monomeric influenza subunit protein vaccines, deliver inadequate protection. On the other hand, macromolecular protein structures, such as capsomers, subviral particles, and/or VLPs, include multiple copies of native proteins exhibiting conformational epitopes, which are advantageous for optimal vaccine immunogenicity.

The present invention describes the cloning of avian influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 genes into a single baculovirus expression vector alone or in tandem and production of influenza vaccine candidates or reagents comprised of recombinant influenza structural proteins that self-assemble into functional and immunogenic homotypic macromolecular protein structures, including subviral influenza particles and influenza VLP, in baculovirus-infected insect cells.

The present invention describes the cloning of human influenza A/Sydney/5/97 and A/Fujian/411/2002 (H3N2) virus HA, NA, M1, M2, and NP genes into baculovirus expression vectors and production influenza vaccine candidates or reagents comprised of influenza structural proteins that self-assemble into functional and immunogenic homotypic macromolecular protein structures, including subviral influenza particles and influenza VLP, in baculovirus-infected insect cells.

In addition, the instant invention describes the cloning of the HA gene of human influenza A/Sydney/5/97 and A/Fujian/411/2002 (H3N2) virus and the HA, NA, and M1 genes of avian influenza A/Hong Kong/1073/99 (H9N2) into a single baculovirus expression vector in tandem and production influenza vaccine candidates or reagents comprised of influenza structural proteins that self-assemble into functional and immunogenic heterotypic macromolecular protein structures, including subviral influenza particles and influenza VLP, in baculovirus-infected insect cells.

VLPs of the Invention and Methods of Making VLPs

In general, virus-like particles (VLPs) lack a viral genome and, therefore, are non-infectious. In addition, virus-like particles can often be produced by heterologous expression and can be easily purified. Most VLPs comprise at least a viral core protein. This core protein usually drives budding and release of particles from a host cell. Examples of such proteins comprise RSV M, influenza M1, HIV gag and vesicular stomatis virus (VSV) M protein. In general, VLPs are useful for preparing antigenic formulation and/or vaccines against infectious agents, e.g. influenza.

However, VLP production has not been particularly efficient. One goal of VLP production is the optimization of culture conditions to obtain the greatest possible productivity. Even incremental increases in productivity can be economically significant and can save lives. The inventors of the present invention have unexpectedly discovered that expressing an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, in a host cell significantly enhances production of VLPs from host cells.

Thus, the invention described herein comprises VLPs comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein (e.g. a protein from an infectious agent). In one embodiment, said non-avian influenza protein is HA and/or NA from a non-avian influenza virus. In another embodiment, said non-avian influenza protein is a seasonal influenza protein. In another embodiment, said HA or NA seasonal influenza are A/Wisconsin/67/2005 and/or A/Fujian/411/02. In another embodiment, said HA or NA has hemagglutinin or neuraminidase activity, respectively. In another embodiment, said non-avian influenza protein is from a virus, bacterium, fungus and/or parasite.

In another embodiment, the invention comprises a VLP consisting essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, and at least one non-avian influenza protein (e.g. a protein from an infectious agent). These VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. For example, these VLPs contain an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, and at least one non-avian influenza protein and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1 and the non-avian influenza protein). In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, and at least one non-avian influenza protein.

Chimeric VLPs of the invention are useful for preparing vaccines and immunogenic compositions. One important feature of said chimeric VLPs is the ability to express proteins on the surface of said VLPs so that the immune system of a vertebrate can induce an immune response against said protein. However, not all proteins can be expressed on the surface of VLPs. There may be many reasons why certain proteins are not expressed, or poorly expressed, on the surface of VLPs. One reason is that said protein is not directed to the membrane of a host cell or that said protein does not have a transmembrane domain. Sequences near the carboxyl terminus of influenza hemagglutinin may be important for incorporation of HA into the lipid bilayer of the mature influenza enveloped nucleocapsids and for the assembly of HA trimer interaction with the influenza core protein M1 (Ali, et al., (2000) J. Virol. 74, 8709-19). Thus, one method of overcoming the inability of expressing non-avian influenza proteins on the surface of VLPs, and/or increasing the expression of said proteins, is to fuse the cytoplasmic and/or the transmembrane domains of influenza HA and/or NA to a non-avian influenza protein thus creating a chimeric protein.

Thus, in one embodiment of the invention, said chimeric VLPs of the invention comprise at least one chimeric protein. In another embodiment, said chimeric protein comprise at least one external domain (ectodomain) of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of a heterologous HA and/or NA. In another embodiment, said heterologous transmembrane and/or cytoplasmic-terminal domains HA and/or NA is from a pandemic, seasonal and/or avian influenza virus. There are 16 different hemagglutinin (HA) and 9 different neuraminidase (NA) all of which have been found among wild birds. Wild birds are the primary natural reservoir for all types of influenza A viruses and are thought to be the source of all types of influenza A viruses in all other vertebrates. These subtypes differ because of changes in the hemagglutinin (HA) and neuraminidase (NA) on their surface. Many different combinations of HA and NA proteins are possible. Each combination represents a different type of influenza A virus. In addition, each type can be further classified into strains based on different mutations found in each of its 8 genes. Thus, in another embodiment, said heterologous transmembrane and/or cytoplasmic-terminal domains HA and/or NA is from a pandemic, seasonal and/or avian influenza virus and a NA from a pandemic, seasonal and/or avian influenza virus, wherein said HA is selected from the group consisting of H1, H2, H3, H4, H5, H6, H,7 H8, H9, H10, H11, H12, H13, H14, H15 and H16 and said NA is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In another embodiment, said non-avian influenza HA and/or NA are from a seasonal influenza strain A/Wisconsin/67/2005 and HA and/or NA transmembrane and/or cytoplasmic-terminal domains are from an avian influenza strain. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Fujian/411/02 and HA and/or NA transmembrane and/or cytoplasmic-terminal domains are from an avian influenza strain. Said HA and/or NA transmembrane and/or cytoplasmic-terminal domains from avian influenza can be derived from the group consisting of influenza virus H9N2 and influenza virus H5N1.

Said HA and/or NA from H9N2 influenza strain can be isolated from any one of the influenza virus from the group consisting of A/quail/Hong Kong/G1/97, A/Hong Kong/1073/99, A/Hong Kong/2108/03, Duck/HK/Y280/97, CK/HK/G9/97, Gf/HK/SSP607/03, Ph/HK/CSW1323/03, WDk/ST/4808/01, CK/HK/NT142/03, CK/HK/WF126/03, SCk/HK/WF285/03, CK/HK/YU463/03, CK/HK/YU577/03, SCk/HK/YU663/03, Ck/HK/CSW161/03, and GF/HK/NT101/03. In one embodiment, said H9N2 influenza strain is A/Hong Kong/1073/99. In another embodiment, said HA and/or NA from influenza strain H5N1 can be from clade 1 and/or clade 2. In another embodiment, said H5N1 is from clade 1. In another embodiment, said H5N1 is from clade 2. In another embodiment, said H5N1 is selected from the group consisting of A/Vietnam/1194/04, A/Vietnam/1203/04, A/Hongkong/213/03, A/Indonesia/2/2005, A/Bar headed goose/Quinghai/1A/2005, A/Anhui/1/2005, and A/Indonesia/5/05. In another embodiment, said H5N1 strain is A/Indonesia/5/05.

Chimeric VLPs of the invention may comprise an avian influenza M1 protein. Said M1 protein can be derived from influenza strain H9N2 or H5N1. Said H9N2 influenza M1 can be isolated from any one of the influenza virus from the group consisting of A/quail/Hong Kong/G1/97, A/Hong Kong/1073/99, A/Hong Kong/2108/03, Duck/HK/Y280/97, CK/HK/G9/97, Gf/HK/SSP607/03, Ph/HK/CSW1323/03, WDk/ST/4808/01, CK/HK/NT142/03, CK/HK/WF126/03, SCk/HK/WF285/03, CK/HK/YU463/03, CK/HK/YU577/03, SCk/HK/YU663/03, Ck/HK/CSW161/03, and GF/HK/NT101/03. In one embodiment, said H9N2 influenza strain is A/Hong Kong/1073/99. In another embodiment, said M1 can be from influenza strain H5N1. In another embodiment, said H5N1 is selected from the group consisting of A/Vietnam/1194/04, A/Vietnam/1203/04, A/Hongkong/213/03, A/Indonesia/2/2005, A/Bar headed goose/Quinghai/1A/2005, A/Anhui/1/2005, and A/Indonesia/5/05. In another embodiment, said H5N1 strain is A/Indonesia/5/05.

In another embodiment of the invention, said chimeric VLPs of the invention comprise chimeric proteins from influenza B viruses. In one embodiment, said chimeric proteins comprise external domains of influenza B HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of a heterologous HA and/or NA cytoplasmic and/or transmembrane region. In another embodiment, said heterologous HA and/or NA is from seasonal influenza A/Wisconsin/67/2005 and/or A/Fujian/411/02 and/or avian influenza A/Indonesia/5/05. In another embodiment, said influenza B viruses are from B/Shanghai/361/2002 and/or B/Hong Kong/330/2001.

In another embodiment of the invention, chimeric VLPs of the invention comprise an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, and at least one protein from another infectious agent (non-avian influenza protein). Said protein from another infectious agent can be a type I and/or a type II protein. A type I protein has a C-terminus located in the cytosol (the transmembrane domain is located near the C-terminus), whereas a type II protein has an N-terminus that is located in the cytosol (the transmembrane domain is located near the N-terminus). In another embodiment, said protein may comprise epitopes that can induce an immune response against said protein when administered to a vertebrate. In another embodiment, said protein can associate with an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein, directly or indirectly. In another embodiment, said protein is expressed on the surface of the VLP. In another embodiment, said protein, or portion thereof, can be fused to a heterologous protein creating a chimeric protein. For example, the external domains of proteins from infective agents, such as non-avian influenza virus, coronavirus, VZV, dengue, or yellow fever and/or other agents can be used to generate chimeric proteins by fusing said proteins from infective agents with a protein that associates with an influenza M1 protein comprising a K¹⁰¹ residue, such as avian M1 protein. In one embodiment, said protein that associates with an influenza M1 protein comprising a K¹⁰¹ residue is an influenza protein. In another embodiment, said protein that associates with the influenza M1 is a HA and/or NA from influenza. In another embodiment, said HA and/or NA is from a seasonal influenza virus. In another embodiment, said HA and/or NA is from an avian influenza virus. In another embodiment, said avian influenza virus is H5N1. In another embodiment, said H5N1 strain is A/Indonesia/5/05. In another embodiment, said infectious agent comprises at least one SARS virus protein. In another embodiment, said SARS virus protein is SARS coronavirus (SARS-CoV) Urbani strain spike (S) protein (NCBI access number AAP13441, SEQ ID NO: 63).

In another embodiment, the invention comprises a VLP comprising a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein from an infective agent. In another embodiment, the transmembrane domain and/or cytoplasmic tail of the HA and/or NA protein extends from the N or C-terminus to approximately 0, 1, 2, 3 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 to about 50 amino acids past the transmembrane domain and is fused to said protein from another infectious agent. In another embodiment, the portion of the protein from another infectious agent that comprises the cytoplasmic and the transmembrane domain is replaced with a cytoplasmic and/or transmembrane domain from an influenza protein (i.e. avian and/or seasonal influenza NA and/or HA). In another embodiment, said seasonal influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and/or A/Fujian/411/02 and/or avian influenza A/Indonesia/5/05. In another embodiment, said M1 is from an avian influenza strain H5N1. In another embodiment, said M1 is from influenza strain A/Indonesia/5/05. In another embodiment, said M1 is from influenza strain H9N2. In another embodiment, said M1 is from influenza strain A/Hong Kong/1073/99. In another embodiment, the transmembrane domain and/or cytoplasmic tail of A/Wisconsin/67/2005 HA and/or NA is fused to a protein from an infectious agent. In another embodiment, the transmembrane domain and/or cytoplasmic tail of A/Fujian/411/02 HA and/or NA is fused to a protein from an infectious agent. In another embodiment, the transmembrane domain and/or cytoplasmic tail of A/Indonesia/5/05 HA and/or NA is fused to a protein from an infectious agent.

In another embodiment, the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein from an infective agent comprises a spacer sequence between the protein segments. Said space sequences can be any amino acid not in the protein. This spacer sequence may be important for expressing said protein from an infective agent on the surface of the VLP. Examples of spacer sequences include a poly-G amino acids. Said spacer can be from 1 to about 100 amino acids long.

In another embodiment of the invention, said VLPs comprise more than one protein from an infectious agent. In this embodiment, said VLPs are multivariant VLPs capable of inducing an immune response to several proteins from infectious agents. In another embodiment said VLPs comprise proteins from at least two different influenza viruses. For example said multivariant VLPs can comprise a HA and/or NA from a seasonal influenza virus A and/or B and/or from an avian influenza virus. This embodiment also comprises the presentation of HA and/or NA of the three influenza viruses (two subtypes of influenza A viruses and one influenza B virus) that are chosen by WHO and the CDC (see above) to be in the flu vaccines for the fall and winter in a single VLP. In another embodiment, said multivariant VLPs comprise proteins from several viruses, bacteria and/or parasites. For example, said VLPs comprise proteins from influenza and RSV, influenza, RSV and parainfluenza. In another embodiment, said proteins are chimeric proteins wherein each protein comprises the HA and/or NA from an influenza virus. In another embodiment, said multivalent VLPs comprise an influenza M1 protein comprising a K¹⁰¹ residue. In one embodiment, the influenza M1 protein comprising a K¹⁰¹ residue is derived from an avian influenza virus strain. In another embodiment, said avian influenza virus strain is A/Indonesia/5/05.

In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent. In another embodiment, said chimeric proteins comprise a fusion between the proteins, or a portion thereof, of two infectious agents or antigenic variations of the same agent. Said fusion protein will comprise antigenic agents from each protein from said infectious agent. In another embodiment, said chimeric protein comprises an amino acid linker between the proteins. An example of this embodiment is a fusion between the influenza HA and the RSV F protein. An example of this embodiment is a fusion between the influenza HA and the RSV F1 protein (e.g. SEQ ID NO: 64). In another embodiment, said chimeric protein comprises the HA and/or NA transmembrane and/or cytoplasmic domain from an avian influenza virus. In another embodiment, said multivalent VLPs comprise an avian influenza M1 protein. In another embodiment, said avian influenza is A/Indonesia/5/05.

In another embodiment of the invention, the chimeric genes encoding the chimeric proteins (as described above), which may be codon optimized, are synthesized and cloned through a series of steps into a bacmid construct followed by rescue of recombinant baculovirus by plaque isolation and expression analyses. The VLPs for each of these targets can then be rescued by co-infection with the use of two recombinant baculoviruses (1) expressing the M1, and (2) expressing the chimeric protein from an infectious agent (e.g. VZV, RSV, dengue, yellow fever) with cytoplasmic and/or transmembrane domain from HA and/or NA from a seasonal and/or avian influenza virus. In another embodiment, the VLPs of the invention can be rescued by infection with the use of a recombinant baculovirus expressing the M1 and the chimeric protein from an infectious agent (e.g. VZV, RSV, dengue, yellow fever) with cytoplasmic and transmembrane domain from influenza HA and/or NA. In one embodiment, the influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, the influenza M1 protein is derived from an avian influenza virus strain. In another embodiment, said avian influenza virus strain is A/Indonesia/5/05.

Infectious agents can be viruses, bacteria, fungi and/or parasites. A protein that may be expressed on the surface of chimeric VLPs of the invention can be derived from viruses, bacteria, fungi and/or parasites. In other embodiments, the proteins expressed on the surface of said chimeric VLPs may be tumor or cancer antigens. The proteins derived from viruses, bacteria, fungi and/or parasites can induce an immune response (cellular and/or humoral) in a vertebrate that which will prevent, treat, manage and/or ameliorate an infectious disease in said vertebrate.

Non-limiting examples of viruses from which said infectious agent proteins can be derived from are the following: coronavirus (e.g. the agent that causes SARS), hepatitis viruses A, B, C, D & E3, human immunodeficiency virus (HIV), herpes viruses 1, 2, 6 & 7, cytomegalovirus, varicella zoster, papilloma virus, Epstein Barr virus, parainfluenza viruses, respiratory syncytial virus (RSV), human metapneumovirus, adenoviruses, bunya viruses (e.g. hanta virus), coxsakie viruses, picoma viruses, rotaviruses, rhinoviruses, rubella virus, mumps virus, measles virus, Rubella virus, polio virus (multiple types), adeno virus (multiple types), parainfluenza virus (multiple types), avian influenza (various types), shipping fever virus, Western and Eastern equine encephalomyelitis, Japanese encephalomyelitis, fowl pox, rabies virus, slow brain viruses, rous sarcoma virus, Papovaviridae, Parvoviridae, Picornaviridae, Poxyiridae (such as Smallpox or Vaccinia), Reoviridae (e.g., Rotavirus), Retroviridae (HTLV-I, HTLV-II, Lentivirus), Togaviridae (e.g., Rubivirus), Newcastle disease virus, West Nile fever virus, Tick borne encephalitis, yellow fever, chikungunya virus, and dengue virus (all serotypes).

In another embodiment, the specific proteins from viruses may comprise: HA and/or NA from influenza virus (including avian), S protein from coronavirus, gp160, gp140 and/or gp41 from HIV, gp I to IV and Vp from varicella zoster, E and preM/M from yellow fever virus, dengue (all serotypes) or any flavivirus. Also included are any proteins from a virus that can induce an immune response (cellular and/or humoral) in a vertebrate that can prevent, treat, manage and/or ameliorate an infectious disease in said vertebrate.

Non-limiting examples of bacteria from which said infectious agent proteins can be derived from are the following: B. pertussis, Leptospira pomona, S. paratyphi A and B, C. diphtheriae, C. tetani, C. botulinum, C. perfringens, C. feseri and other gas gangrene bacteria, B. anthracis, P. pestis, P. multocida, Neisseria meningitidis, N gonorrheae, Hemophilus influenzae, Actinomyces (e.g., Norcardia), Acinetobacter, Bacillaceae (e.g., Bacillus anthrasis), Bacteroides (e.g., Bacteroides fragilis), Blastomycosis, Bordetella, Borrelia (e.g., Borrelia burgdorferi), Brucella, Campylobacter, Chlamydia, Coccidioides, Corynebacterium (e.g., Corynebacterium diptheriae), E. coli (e.g., Enterotoxigenic E. coli and Enterohemorrhagic E. coli), Enterobacter (e.g. Enterobacter aerogenes), Enterobacteriaceae (Klebsiella, Salmonella (e.g., Salmonella typhi, Salmonella enteritidis, Serratia, Yersinia, Shigella), Erysipelothrix, Haemophilus (e.g., Haemophilus influenza type B), Helicobacter, Legionella (e.g., Legionella pneumophila), Leptospira, Listeria (e.g., Listeria monocytogenes), Mycoplasma, Mycobacterium (e.g., Mycobacterium leprae and Mycobacterium tuberculosis), Vibrio (e.g., Vibrio cholerae), Pasteurellacea, Proteus, Pseudomonas (e.g., Pseudomonas aeruginosa), Rickettsiaceae, Spirochetes (e.g., Treponema spp., Leptospira spp., Borrelia spp.), Shigella spp., Meningiococcus, Pneumococcus and Streptococcus (e.g., Streptococcus pneumoniae and Groups A, B, and C Streptococci), Ureaplasmas. Treponema pollidum, Staphylococcus aureus, Pasteurella haemolytica, Corynebacterium diptheriae toxoid, Meningococcal polysaccharide, Bordetella pertusis, Streptococcus pneumoniae, Clostridium tetani toxoid, and Mycobacterium bovis.

Non-limiting examples of parasites from which said infectious agent proteins can be derived from are the following: leishmaniasis (Leishmania tropica mexicana, Leishmania tropica, Leishmania major, Leishmania aethiopica, Leishmania braziliensis, Leishmania donovani, Leishmania infantum, Leishmania chagasi), trypanosomiasis (Trypanosoma brucei gambiense, Trypanosoma brucei rhodesiense), toxoplasmosis (Toxoplasma gondii), schistosomiasis (Schistosoma haematobium, Schistosoma japonicum, Schistosoma mansoni, Schistosoma mekongi, Schistosoma intercalatum), malaria (Plasmodium virax, Plasmodium falciparium, Plasmodium malariae and Plasmodium ovale) Amebiasis (Entamoeba histolytica), Babesiosis (Babesiosis microti), Cryptosporidiosis (Cryptosporidium parvum), Dientamoebiasis (Dientamoeba fragilis), Giardiasis (Giardia lamblia), Helminthiasis and Trichomonas (Trichomonas vaginalis).

Non-limiting examples of fungi from which said glycoproteins can be derived are from the following: Absidia (e.g. Absidia corymbifera), Ajellomyces (e.g. Ajellomyces capsulatus, Ajellomyces dermatitidis), Arthroderma (e.g. Arthroderma benhamiae, Arthroderma fulvum, Arthroderma gypseum, Arthroderma incurvatum, Arthroderma otae, Arthroderma vanbreuseghemii), Aspergillus (e.g. Aspergillus fumigatus, Aspergillus niger), Candida (e.g. Candida albicans, Candida albicans var. stellatoidea, Candida dublinensis, Candida glabrata, Candida guilliermondii (Pichia guilliermondii), Candida krusei (Issatschenkia orientalis), Candida parapsilosis, Candida pelliculosa (Pichia anomala), Candida tropicalis, Coccidioides (e.g. Coccidioides immitis), Cryptococcus (e.g. Cryptococcus neoformans (Filobasidiella neoformans), Histoplasma (e.g. Histoplasma capsulatum (Ajellomyces capsulatus), Microsporum (e.g. Microsporum canis (Arthroderma otae), Microsporum fulvum (Arthroderma fulvum), Microsporum gypseum, Genus Pichia (e.g. Pichia anomala, Pichia guilliermondii), Pneumocystis (e.g. Pneumocystis jirovecii), Cryptosporidium, Malassezia furfur, Paracoccidiodes.

The above lists are meant to be illustrative and by no means are meant to limit the invention to those particular bacterial, viral or parasitic organisms.

The inventors discovered that the use of influenza M1 proteins comprising a K¹⁰¹ residue in the putative L-domain sequence (YXXL at amino acid positions 100-103) results in highly efficient VLP production. Moreover, the present inventors have discovered this K¹⁰¹ residue as part of the putative L-domain is found almost exclusively in avian M1 proteins. Thus, in one aspect, the present invention provides VLPs comprising an influenza M1 protein which comprises a lysine at the second position (e.g. position 101) of the M1 protein L-domain. In one embodiment, the L-domain comprises the sequence of YKKL. In another embodiment, the M1 protein comprising a lysine at the second position of the M1 protein L domain (e.g. YKKL) exhibits increased VLP formation efficiency as compared to an M1 protein comprising an arginine at the second position of the M1 protein L domain (e.g. YRKL). In another embodiment, the increased VLP formation efficiency using an M1 protein comprising a K¹⁰¹ residue in the putative L-domain sequence is at least an about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100%, about 120%, about 140%, about 160%, about 180%, about 200%, about 500%, or about 1000% more than a corresponding M1 protein without the K¹⁰¹ residue substitution. In one embodiment, the VLP comprising an influenza M1 with a K¹⁰¹ residue in the putative L-domain sequence further comprises an influenza HA and/or NA protein. In another embodiment, said HA and/or NA protein is from a pandemic, seasonal, or avian influenza virus. In another embodiment, the VLP comprising an influenza M1 with a K¹⁰¹ residue in the putative L-domain sequence further comprises a heterologous protein (e.g., a non-avian influenza protein as described above).

The invention also encompasses variants of the said proteins expressed on or in the chimeric VLPs of the invention. The variants may contain alterations in the amino acid sequences of the constituent proteins. The term “variant” with respect to a protein refers to an amino acid sequence that is altered by one or more amino acids with respect to a reference sequence. The variant can have “conservative” changes, wherein a substituted amino acid has similar structural or chemical properties, e.g., replacement of leucine with isoleucine. Alternatively, a variant can have “nonconservative” changes, e.g., replacement of a glycine with a tryptophan. Analogous minor variations can also include amino acid deletion or insertion, or both. Guidance in determining which amino acid residues can be substituted, inserted, or deleted without eliminating biological or immunological activity can be found using computer programs well known in the art, for example, DNASTAR software.

Natural variants can occur due to mutations in the proteins. These mutations may lead to antigenic variability within individual groups of infectious agents, for example influenza. Thus, a person infected with an influenza strain develops antibody against that virus, as newer virus strains appear, the antibodies against the older strains no longer recognize the newer virus and reinfection can occur. The invention encompasses all antigenic and genetic variability of proteins from infectious agents for making chimeric VLPs.

General texts which describe molecular biological techniques, which are applicable to the present invention, such as cloning, mutation, cell culture and the like, include Berger and Kimmel, Guide to Molecular Cloning Techniques, Methods in Enzymology, Vol. 152 Academic Press, Inc., San Diego, Calif. (“Berger”); Sambrook et al., Molecular Cloning—A Laboratory Manual (3rd Ed.), Vol. 1-3, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 2000 (“Sambrook”) and Current Protocols in Molecular Biology, F. M. Ausubel et al., eds., Current Protocols, a joint venture between Greene Publishing Associates, Inc. and John Wiley & Sons, Inc., (“Ausubel”). These texts describe mutagenesis, the use of vectors, promoters and many other relevant topics related to, e.g., the cloning and mutating HA, NA and/or proteins from infectious agents, etc. Thus, the invention also encompasses using known methods of protein engineering and recombinant DNA technology to improve or alter the characteristics of the proteins expressed on or in the VLPs of the invention. Various types of mutagenesis can be used to produce and/or isolate variant nucleic acids that encode for protein molecules and/or to further modify/mutate the proteins in or on the VLPs of the invention. They include but are not limited to site-directed, random point mutagenesis, homologous recombination (DNA shuffling), mutagenesis using uracil containing templates, oligonucleotide-directed mutagenesis, phosphorothioate-modified DNA mutagenesis, mutagenesis using gapped duplex DNA or the like. Additional suitable methods include point mismatch repair, mutagenesis using repair-deficient host strains, restriction-selection and restriction-purification, deletion mutagenesis, mutagenesis by total gene synthesis, double-strand break repair, and the like. Mutagenesis, e.g., involving chimeric constructs, is also included in the present invention. In one embodiment, mutagenesis can be guided by known information of the naturally occurring molecule or altered or mutated naturally occurring molecule, e.g., sequence, sequence comparisons, physical properties, crystal structure or the like.

The invention further comprises protein variants which show substantial biological activity, e.g., able to elicit an effective antibody response when expressed on or in VLPs of the invention. Such variants include deletions, insertions, inversions, repeats, and substitutions selected according to general rules known in the art so as have little effect on activity.

Methods of cloning said proteins are known in the art. For example, the gene encoding a specific virus protein can be isolated by RT-PCR from polyadenylated mRNA extracted from cells which had been infected with a virus (DNA or RNA virus) or PCR from cells which had been infected with a DNA virus. The resulting product gene can be cloned as a DNA insert into a vector. The term “vector” refers to the means by which a nucleic acid can be propagated and/or transferred between organisms, cells, or cellular components. Vectors include plasmids, viruses, bacteriophages, pro-viruses, phagemids, transposons, artificial chromosomes, and the like, that replicate autonomously or can integrate into a chromosome of a host cell. A vector can also be a naked RNA polynucleotide, a naked DNA polynucleotide, a polynucleotide composed of both DNA and RNA within the same strand, a poly-lysine-conjugated DNA or RNA, a peptide-conjugated DNA or RNA, a liposome-conjugated DNA, or the like, that is not autonomously replicating. In many, but not all, common embodiments, the vectors of the present invention are plasmids or bacmids.

Thus, the invention comprises nucleotides that encode proteins, including chimeric molecules, cloned into an expression vector that can be expressed in a cell that induces the formation of VLPs of the invention. An “expression vector” is a vector, such as a plasmid that is capable of promoting expression, as well as replication of a nucleic acid incorporated therein. Typically, the nucleic acid to be expressed is “operably linked” to a promoter and/or enhancer, and is subject to transcription regulatory control by the promoter and/or enhancer. In one embodiment, said nucleotides that encode for HA from an avian, pandemic and/or seasonal influenza virus is selected from the group consisting of H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 and H16. In another embodiment, said nucleotides that encode for NA from an avian, pandemic and/or seasonal influenza virus, is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In another embodiment, said vector comprises nucleotides that encode the HA, NA and/or M1 influenza protein. In another embodiment, said vector consists of nucleotides that encodes the HA, NA and M1 influenza protein. A preferred expression vector is a baculovirus vector. After the nucleotides encoding said influenza proteins have been cloned said nucleotides can be further manipulated. For example, a person with skill in the art can mutate specific bases in the coding region to produce variants. The variants may contain alterations in the coding regions, non-coding regions, or both. Such variants may increase the immunogenticity of an influenza protein or remove a splice site from a protein or RNA. For example, in one embodiment, the donor and acceptor splicing sites on the influenza M protein (full length) are mutated to prevent splicing of the M mRNA into M1 and M2 transcripts. In another embodiment the HA is engineered to remove or mutate the cleavage site. For example, wild type H5 HA has a cleavage site that contains multiple basic amino acids (RRRKR, SEQ ID NO: 59). This wild type sequence makes the HA more susceptible to multiple ubiquitous proteases that may be present in host or system expression these HAs. In one embodiment, removing these amino acids can reduce the susceptibility of the HA to various proteases. In another embodiment, the cleavage site can be mutated to remove the cleavage site (e.g. mutate to RESR SEQ ID NO: 60).

In one embodiment, said nucleotides encode for a non-avian influenza protein and/or chimeric protein (as discussed above). In another embodiment, the expression vector comprises nucleotides that encode for a non-avian influenza protein and/or chimeric protein and an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein. In another embodiment, said vector comprises nucleotides that encode a chimeric protein comprising the cytoplasmic and/or the transmembrane domain of HA and/or NA from avian and/or seasonal influenza protein. In another embodiment, said seasonal influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA are from influenza strain A/Indonesia/5/05. In another embodiment, said vector comprises nucleotides that encode M1 from influenza strain A/Indonesia/5/05 and a chimeric protein comprising the A/Wisconsin/67/2005 (seasonal influenza) cytoplasmic and/or the transmembrane from HA and/or NA. In another embodiment, said vector comprises nucleotides that encode M1 from influenza strain A/Indonesia/5/05 and a chimeric protein comprising the A/Indonesia/5/05 (avian influenza) cytoplasmic and/or the transmembrane from HA and/or NA. In another embodiment, an influenza NA nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99° A identical to SEQ ID NOs. 1, 11, 38, 39, 46, 47, 54, 55, 65, 66, 67, 68, or 79. In another embodiment, an influenza HA nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to SEQ ID NOs. 2, 10, 27, 28, 29, 30, 33, 34, 35, 36, 37, 42, 43, 44, 45, 50, 51, 52, 53, 69, 70, 71, 72, 73, or 78. In another embodiment, an influenza M1 nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to SEQ ID NOs. 3, 12, 40, 41, 48, 49, 74, 75, 76, or 77. In another embodiment, a S nucleic acid or protein is at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to SEQ ID NOs. 62 or 63.

In some embodiments, said proteins may comprise, mutations containing alterations that produce silent substitutions, additions, or deletions, but do not alter the properties or activities of the encoded protein or how the proteins are made. Nucleotide variants can be produced for a variety of reasons, e.g., to optimize codon expression for a particular host (change codons in the human mRNA to those preferred by insect cells such as Sf9 cells). See U.S. patent publication 2005/0118191, herein incorporated by reference in its entirety for all purposes. Examples of optimized codon sequences of the invention are disclosed below (e.g. SEQ ID 42, 44, 46, 48, 50, 52, and 54).

In addition, the nucleotides can be sequenced to ensure that the correct coding regions were cloned and do not contain any unwanted mutations. The nucleotides can be subcloned into an expression vector (e.g. baculovirus) for expression in any cell. The above is only one example of how the influenza proteins (including chimeric proteins) can be cloned. A person with skill in the art understands that additional methods are available and are possible.

The invention also provides for constructs and/or vectors that comprise nucleotides that encode for an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 proteins, and non-avian influenza proteins and/or chimeric proteins (as described above). The constructs and/or vectors that comprise avian M1 and non-avian influenza proteins and/or chimeric proteins, should be operatively linked to an appropriate promoter, such as the AcMNPV polyhedrin promoter (or other baculovirus), phage lambda PL promoter, the E. coli lac, phoA and tac promoters, the SV40 early and late promoters, and promoters of retroviral LTRs are non-limiting examples. Other suitable promoters will be known to the skilled artisan depending on the host cell and/or the rate of expression desired. The expression constructs will further contain sites for transcription initiation, termination, and, in the transcribed region, a ribosome-binding site for translation. The coding portion of the transcripts expressed by the constructs will preferably include a translation initiating codon at the beginning and a termination codon appropriately positioned at the end of the polypeptide to be translated.

Expression vectors will preferably include at least one selectable marker. Such markers include dihydrofolate reductase, G418, or neomycin resistance for eukaryotic cell culture and tetracycline, kanamycin, or ampicillin resistance genes for culturing in E. coli and other bacteria. Among vectors preferred are virus vectors, such as baculovirus, poxvirus (e.g., vaccinia virus, avipox virus, canarypox virus, fowlpox virus, raccoonpox virus, swinepox virus, etc.), adenovirus (e.g., canine adenovirus), herpesvirus, and retrovirus. Other vectors that can be used with the invention comprise vectors for use in bacteria, which comprise pQE70, pQE60 and pQE-9, pBluescript vectors, Phagescript vectors, pNH8A, pNH16a, pNH18A, pNH46A, ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5. Among preferred eukaryotic vectors are pFastBac1 pWINEO, pSV2CAT, pOG44, pXT1, and pSG, pSVK3, pBPV, pMSG, and pSVL. Other suitable vectors will be readily apparent to the skilled artisan.

Next, the recombinant constructs mentioned above could be used to transfect, infect, or transform and can express avian M1 and a non-avian influenza protein and/or chimeric proteins, into eukaryotic cells and/or prokaryotic cells. Thus, the invention provides for host cells that comprise a vector (or vectors) that contain nucleic acids which code for avian M1 and chimeric proteins, and permit the expression of said constructs in said host cell under conditions which allow the formation of VLPs.

Among eukaryotic host cells are yeast, insect, avian, plant, C. elegans (or nematode), and mammalian host cells. Non limiting examples of insect cells are, Spodoptera frugiperda (Sf) cells, e.g. Sf9, Sf21, Trichoplusia ni cells, e.g. High Five cells, and Drosophila S2 cells. Examples of fungi (including yeast) host cells are S. cerevisiae, Kluyveromyces lactis (K. lactis), species of Candida including C. albicans and C. glabrata, Aspergillus nidulans, Schizosaccharomyces pombe (S. pombe), Pichia pastoris, and Yarrowia lipolytica. Examples of mammalian cells are COS cells, baby hamster kidney cells, mouse L cells, LNCaP cells, Chinese hamster ovary (CHO) cells, human embryonic kidney (HEK) cells, and African green monkey cells, CV1 cells, HeLa cells, MDCK cells, Vero, and Hep-2 cells. Xenopus laevis oocytes, or other cells of amphibian origin, may also be used. Prokaryotic host cells include bacterial cells, for example, E. coli, B. subtilis, and mycobacteria.

Vectors, e.g., vectors comprising polynucleotides of avian M1 and non-avian influenza proteins and/or chimeric proteins, can be transfected into host cells according to methods well known in the art. For example, introducing nucleic acids into eukaryotic cells can be by calcium phosphate co-precipitation, electroporation, microinjection, lipofection, and transfection employing polyamine transfection reagents. In one embodiment, said vector is a recombinant baculovirus. In another embodiment, said recombinant baculovirus is transfected into a eukaryotic cell. In a preferred embodiment, said cell is an insect cell. In another embodiment, said insect cell is a Sf9 cell.

In another embodiment, said vector and/or host cell comprise nucleotides that encode an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 proteins, and non-avian influenza proteins and/or chimeric proteins. In another embodiment, said vector and/or host cell consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 proteins, and non-avian influenza proteins and/or chimeric proteins. In a further embodiment, said vector and/or host cell consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 proteins, and non-avian influenza proteins and/or chimeric proteins. These vector and/or host cell contain an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 proteins, and non-avian influenza proteins and/or chimeric proteins, and may contain additional markers, such as an origin of replication, selection markers, etc.

The invention also provides for constructs and methods that will further increase the efficiency of VLP production. For example, the addition of leader sequences to the influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and non-avian influenza proteins and/or chimeric proteins, can improve the efficiency of protein transporting within the cell. For example, a heterologous signal sequence can be fused to the M1 protein and non-avian influenza proteins and/or chimeric proteins. In one embodiment, the signal sequence can be derived from the gene of an insect preprotein and fused to the M1 and non-avian influenza proteins and/or chimeric proteins. In another embodiment, the signal peptide is the chitinase signal sequence, which works efficiently in baculovirus expression systems.

Influenza VLPs of the invention are useful for preparing vaccines against influenza viruses. One important feature of this system is the ability to replace the surface glycoproteins with different subtypes of HA and/or NA or other viral proteins, thus, allowing updating of new influenza antigenic variants every year or to prepare for an influenza pandemic. As antigenic variants of these glycoproteins are identified, the VLPs can be updated to include these new variants (e.g. for seasonal influenza vaccines). In addition, surface glycoproteins from potentially pandemic viruses, such as H5N1, or other HA, NA combinations with pandemic potential could be incorporated into VLPs without concern of releasing genes that had not circulated in humans for several decades. This is because the VLPs are not infectious, do not replicate and cannot cause disease. Thus, this system allows for creating a new candidate influenza vaccine every year and/or an influenza pandemic vaccine whenever it is necessary.

There are 16 different hemagglutinin (HA) and 9 different neuraminidase (NA) all of which have been found among wild birds. Wild birds are the primary natural reservoir for all types of influenza A viruses and are thought to be the source of all types of influenza A viruses in all other vertebrates. These subtypes differ because of changes in the hemagglutinin (HA) and neuraminidase (NA) on their surface. Many different combinations of HA and NA proteins are possible. Each combination represents a different type of influenza A virus. In addition, each type can be further classified into strains based on different mutations found in each of its 8 genes.

All known types of influenza A viruses can be found in birds. Usually avian influenza viruses do not infect humans. However, some avian influenza viruses develop genetic variations associated with the capability of crossing the species barrier. Such a virus is capable of causing a pandemic because humans have no natural immunity to the virus and can easily spread from person to person. In 1997, avian influenza virus jumped from a bird to a human in Hong Kong during an outbreak of bird flu in poultry. This virus was identified as influenza virus H5N1. The virus caused severe respiratory illness in 18 people, six of whom died. Since that time, many more cases of known H5N1 infections have occurred among humans worldwide; approximately half of those people have died.

Thus, the present invention encompasses the cloning of HA, NA and M1 nucleotides from avian influenza viruses, influenza viruses with pandemic potential and/or seasonal influenza viruses into expression vectors. The present invention also describes the production of influenza vaccine candidates or reagents comprised of influenza proteins that self-assemble into functional VLPs. All combinations of viral proteins must be co-expressed with a M1 nucleotide.

VLPs of the invention consist or comprise influenza HA, NA and M1 proteins. In one embodiment, said VLP comprises a HA from an avian, pandemic and/or seasonal influenza virus and a NA from an avian, pandemic and/or seasonal influenza virus, wherein said HA is selected from the group consisting of H1, H2, H3, H4, H5, H6, H,7 H8, H9, H10, H11, H12, H13, H14, H15 and H16 and said NA is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In another embodiment, the invention comprises a VLP that consists essentially of HA, NA and M1. Said HA and NA can be from the above list of HA and NA. These VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, the HA and/or the NA may exhibit hemagglutinin activity and/or neuraminidase activity, respectively, when expressed on the surface of VLPs.

In another embodiment, said VLP comprises HA and NA of the H5N1 virus and a M1 protein (the M1 protein may or may not be from the same viral strain). In another embodiment, said VLP consists essentially of HA, NA of the H5N1 virus and a M1 protein. These VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In a further embodiment, said VLP consists of HA, NA of the H5N1 virus and a M1 protein. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of H5, N1 and M1 proteins. These VLPs contain H5, N9 and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, H5 and/or N1). In another embodiment, the H5 and/or the N1 may exhibit hemagglutinin activity and/or neuraminidase activity, respectively, when expressed on the surface of VLPs.

In another embodiment, said VLP comprises the HA and NA of the H9N2 virus, and a M1 protein. In another embodiment, said VLP consists essentially of the HA and NA of the H9N2 virus, and a M1 protein. These VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, said VLP consists of the HA and NA of the H9N2 virus, and a M1 protein. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of H9, N2 and M1 proteins. These VLPs contain H9, N2 and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, H9 and/or N2). In another embodiment, the H9 and/or the N2 may exhibit hemagglutinin activity and/or neuraminidase activity, respectively, when expressed on the surface of VLPs.

In another embodiment, said VLP comprises the HA and NA from an influenza B virus, and a M1 protein. Influenza B viruses are usually found only in humans. Unlike influenza A viruses, these viruses are not classified according to subtype. Influenza B viruses can cause morbidity and mortality among humans, but in general are associated with less severe epidemics than influenza A viruses. In another embodiment, said VLP consists essentially of the HA and NA of the influenza B virus, and a M1 protein. These VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, said VLP consists of the HA and NA of the influenza B virus, and a M1 protein. In another embodiment, the HA and/or the NA may exhibit hemagglutinin activity and/or neuraminidase activity, respectively, when expressed on the surface of VLPs.

The invention also encompasses variants of the said influenza proteins expressed on or in the VLPs of the invention. The variants may contain alterations in the amino acid sequences of the constituent proteins. The term “variant” with respect to a polypeptide refers to an amino acid sequence that is altered by one or more amino acids with respect to a reference sequence. The variant can have “conservative” changes, wherein a substituted amino acid has similar structural or chemical properties, e.g., replacement of leucine with isoleucine. Alternatively, a variant can have “nonconservative” changes, e.g., replacement of a glycine with a tryptophan. Analogous minor variations can also include amino acid deletion or insertion, or both. Guidance in determining which amino acid residues can be substituted, inserted, or deleted without eliminating biological or immunological activity can be found using computer programs well known in the art, for example, DNASTAR software.

Natural variants can occur due to antigenic drifts. Antigenic drifts are small changes in the viral proteins that happen continually over time. Thus, a person infected with a particular flu virus strain develops antibody against that virus, as newer virus strains appear, the antibodies against the older strains no longer recognize the newer virus and reinfection can occur. This is why there is a new vaccine for influenza each season. In addition, some changes in an influenza virus can cause influenza virus to cross species. For example, some avian influenza viruses developed genetic variations associated with the capability of crossing the species barrier. Such a virus is capable of causing a pandemic because people have no natural immunity to the virus and the virus can easily spread from person to person. These naturally occurring variations of the influenza proteins are an embodiment of the invention.

The invention also utilizes nucleic acid and polypeptides which encode NA, HA and M1. In one embodiment, an influenza NA nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99° A identical to SEQ ID NOs 1, 11, 31, 32, 38, 39, 46, 47, 54, 55, 65, 66, 67, or 68. In another embodiment, an influenza HA nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to SEQ ID NOs 2, 10, 27, 28, 29, 30, 33, 34, 35, 36, 37, 42, 43, 44, 45, 50, 51, 52, 53, 56, 57, 58, 69, 70, 71, 72, or 73. In another embodiment, an influenza M1 nucleic acid or protein is at least 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to SEQ ID NOs 3, 12, 40, 41, 48, 49, 74, 75, 76, or 77.

In one embodiment, the vectors and/or host cells of the invention comprise nucleotides which encode an avian, pandemic and/or seasonal influenza virus HA protein selected from the group consisting of H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 and H16. In another embodiment, said vector and/or host cells comprise nucleotides which encode an NA protein which is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In another embodiment, said vector and/or host cell comprises influenza HA, M1 and/or NA. In another embodiment, said vector and/or host cell consists essentially of HA, M1 and/or NA. In a further embodiment, said vector and/or host cell consists of influenza protein comprising HA, M1 and NA. These vector and/or host cell contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, said nucleotides encode for an HA and/or the NA that exhibits hemagglutinin activity and/or neuraminidase activity, respectively, when expressed on the surface of VLPs.

This invention also provides for constructs and methods that will increase the efficiency of VLPs production. For example, removing cleavage sites from proteins in order to increase protein expression (see above). Other method comprises the addition of leader sequences to the HA, NA and/or M1 protein for more efficient transporting. For example, a heterologous signal sequence can be fused to the HA, NA and/or M1 influenza protein. In one embodiment, the signal sequence can be derived from the gene of an insect cell and fused to the influenza HA protein (for expression in insect cells). In another embodiment, the signal peptide is the chitinase signal sequence, which works efficiently in baculovirus expression systems. In other embodiment, interchanging leader sequences between influenza proteins can provide better protein transport. For example, it has been shown that H5 hemagglutinin is less efficient at being transported to the surface of particles. H9 hemagglutinins, however, targets the surface and is integrated into the surface more efficiently. Thus, in one embodiment, the H9 leader sequence is fused to the H5 protein.

Another method to increase efficiency of VLP production is to codon optimize the nucleotides that encode HA, NA and/or M1 proteins for a specific cell type. For example, codon optimizing nucleic acids for expression in Sf9 cell (see U.S. patent publication 2005/0118191, herein incorporated by reference in its entirety for all purposes). Examples of optimized codon sequences for Sf9 cells are disclosed below (e.g. SEQ ID 42, 44, 46, 48, 50, 52, and 54). In one embodiment, the nucleic acid sequence of codon optimized influenza protein is at least 85%, 90%, 95%, 96, 97, 98, or 99% to any one of SEQ ID Nos. 42, 44, 46, 48, 50, 52, and 54.

The invention also comprises a method of increasing the efficiency of producing chimeric VLPs comprising expressing an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein in a host cell. In one embodiment, said VLP comprises HA and/or NA from a non-avian influenza virus. In another embodiment, said non-avian influenza protein is a seasonal influenza protein. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian HA and/or NA. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA are from influenza strain A/Indonesia/5/05. In another embodiment, said M1 is from influenza strain A/Indonesia/5/05. In another embodiment, said HA and/or NA is from influenza strain A/Wisconsin/67/2005. In another embodiment, said avian M1 comprises a lysine at the second position of the M1 protein L domain. In another embodiment, the putative L-domain comprises the sequence YKKL.

In another embodiment of the invention, the increase in VLP production, for chimeric or non-chimeric VLPs, is about 2-fold, about 4-fold, about 8-fold, about 16-fold, about 20-fold, about 25-fold, about 30-fold, about 35-fold, about 40-fold, about 45-fold, about 50-fold, about 55-fold, about 60-fold, about 65-fold, about 70-fold, about 75-fold, about 80-fold, about 85-fold, about 90-fold, about 95-fold, about 100-fold, or more when compared to VLP production using an M1 protein that does not harbor the putative L-domain sequence YKKL under similar conditions, for instance a human seasonal influenza M1. In one embodiment, the efficiency of producing influenza VLPs is increase by about 10%, about 20% about 30%, about 40%, about 50% about 60%, about 70% about 80%, about 90%, about 100%, about 150%, about 200%, about 250%, about 300%, about 350%, about 400%, about 450%, about 500%, about 550%, about 600%, about 650%, about 700%, about 750%, about 800%, about 850%, about 900%, about 950%, about 1000%, or more when compared to VLP production using an M1 protein that does not harbor the putative L-domain sequence YKKL under similar conditions. In a preferred embodiment, the M1 is from the avian influenza virus strain A/Indonesia/5/05 (SEQ ID NO: 49).

The invention also provides for methods of producing VLPs of the invention, said methods comprising expressing an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and a non-avian influenza protein (e.g. seasonal HA and/or NA) under conditions that allow the formation of VLPs. Depending on the expression system and host cell selected, VLPs are produced by growing host cells transformed by an expression vector under conditions whereby the recombinant proteins (e.g. an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and a non-avian influenza protein) are expressed and VLPs are formed. The selection of the appropriate growth conditions is within the skill or a person with skill of one of ordinary skill in the art.

Methods to grow cells engineered to produce VLPs of the invention include, but are not limited to, batch, batch-fed, continuous and perfusion cell culture techniques. Cell culture means the growth and propagation of cells in a bioreactor (a fermentation chamber) where cells propagate and express protein (e.g. recombinant proteins) for purification and isolation. Typically, cell culture is performed under sterile, controlled temperature and atmospheric conditions in a bioreactor. A bioreactor is a chamber used to culture cells in which environmental conditions such as temperature, atmosphere, agitation and/or pH can be monitored. In one embodiment, said bioreactor is a stainless steel chamber. In another embodiment, said bioreactor is a pre-sterilized plastic bag (e.g. Cellbag®, Wave Biotech, Bridgewater, N.J.). In other embodiment, said pre-sterilized plastic bags are about 50 L to 1000 L.

VLPs are then isolated using methods that preserve the integrity thereof, such as by gradient centrifugation, e.g., cesium chloride, sucrose and iodixanol, as well as standard purification techniques including, e.g., ion exchange and gel filtration chromatography.

The following is an example of how VLPs of the invention can be made, isolated and purified. Usually VLPs are produced from recombinant cell lines engineered to create a VLP when said cells are grown in cell culture (see above). A person of skill in the art would understand that there are additional methods that can be utilized to make and purify VLPs of the invention, thus the invention is not limited to the method described.

Production of VLPs of the invention can start by seeding Sf9 cells (non-infected) into shaker flasks, allowing the cells to expand and scaling up as the cells grow and multiply (for example from a 125 ml flask to a 50 L Wave bag). The medium used to grow the cell is formulated for the appropriate cell line (preferably serum free media, e.g. insect medium ExCe11-420, JRH). Next, said cells are infected with recombinant baculovirus at the most efficient multiplicity of infection (e.g. from about 1 to about 3 plaque forming units per cell). Once infection has occurred, the influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one avian influenza heterologous protein are expressed from the virus genome, self assemble into VLPs and are secreted from the cells approximately 24 to 72 hours post infection. Usually, infection is most efficient when the cells are in mid-log phase of growth (4-8×10⁶ cells/ml) and are at least about 90% viable.

VLPs of the invention can be harvested approximately 48 to 96 hours post infection, when the levels of VLPs in the cell culture medium are near the maximum but before extensive cell lysis. The Sf9 cell density and viability at the time of harvest can be about 0.5×10⁶ cells/ml to about 1.5×10⁶ cells/ml with at least 20% viability, as shown by dye exclusion assay. Next, the medium is removed and clarified. NaCl can be added to the medium to a concentration of about 0.4 to about 1.0 M, preferably to about 0.5 M, to avoid VLP aggregation. The removal of cell and cellular debris from the cell culture medium containing VLPs of the invention can be accomplished by tangential flow filtration (TFF) with a single use, pre-sterilized hollow fiber 0.5 or 1.00 μm filter cartridge or a similar device.

Next, VLPs in the clarified culture medium can be concentrated by ultrafiltration using a disposable, pre-sterilized 500,000 molecular weight cut off hollow fiber cartridge. The concentrated VLPs can be diafiltrated against 10 volumes pH 7.0 to 8.0 phosphate-buffered saline (PBS) containing 0.5 M NaCl to remove residual medium components.

The concentrated, diafiltered VLPs can be further purified on a 20% to 60% discontinuous sucrose gradient in pH 7.2 PBS buffer with 0.5 M NaCl by centrifugation at 6,500×g for 18 hours at about 4° C. to about 10° C. Usually VLPs will form a distinctive visible band between about 30% to about 40% sucrose or at the interface (in a 20% and 60% step gradient) that can be collected from the gradient and stored. This product can be diluted to comprise 200 mM of NaCl in preparation for the next step in the purification process. This product contains VLPs and may contain intact baculovirus particles.

Further purification of VLPs can be achieved by anion exchange chromatography, or 44% isopycnic sucrose cushion centrifugation. In anion exchange chromatography, the sample from the sucrose gradient (see above) is loaded into column containing a medium with an anion (e.g. Matrix Fractogel EMD TMAE) and eluted via a salt gradient (from about 0.2 M to about 1.0 M of NaCl) that can separate the VLP from other contaminates (e.g. baculovirus and DNA/RNA). In the sucrose cushion method, the sample comprising the VLPs is added to a 44% sucrose cushion and centrifuged for about 18 hours at 30,000 g. VLPs form a band at the top of 44% sucrose, while baculovirus precipitates at the bottom and other contaminating proteins stay in the 0% sucrose layer at the top. The VLP peak or band is collected.

The intact baculovirus can be inactivated, if desired. Inactivation can be accomplished by chemical methods, for example, formalin or β-propyl lactone (BPL). Removal and/or inactivation of intact baculovirus can also be largely accomplished by using selective precipitation and chromatographic methods known in the art, as exemplified above. Methods of inactivation comprise incubating the sample containing the VLPs in 0.2% of BPL for 3 hours at about 25° C. to about 27° C. The baculovirus can also be inactivated by incubating the sample containing the VLPs at 0.05% BPL at 4° C. for 3 days, then at 37° C. for one hour.

After the inactivation/removal step, the product comprising VLPs can be run through another diafiltration step to remove any reagent from the inactivation step and/or any residual sucrose, and to place the VLPs into the desired buffer (e.g. PBS). The solution comprising VLPs can be sterilized by methods known in the art (e.g. sterile filtration) and stored in the refrigerator or freezer.

The above techniques can be practiced across a variety of scales. For example, T-flasks, shake-flasks, spinner bottles, up to industrial sized bioreactors. The bioreactors can comprise either a stainless steel tank or a pre-sterilized plastic bag (for example, the system sold by Wave Biotech, Bridgewater, N.J.). A person with skill in the art will know what is most desirable for their purposes.

Expansion and production of baculovirus expression vectors and infection of cells with recombinant baculovirus to produce recombinant influenza VLPs can be accomplished in insect cells, for example Sf9 insect cells as previously described. In a preferred embodiment, the cells are Sf9 infected with recombinant baculovirus engineered to produce VLPs of the invention.

Pharmaceutical or Vaccine Formulations and Administration

The invention comprises an antigenic formulation comprising a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP comprises HA and/or NA from a non-avian influenza virus. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian HA and/or NA cytoplasmic region. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA are from influenza strain A/Indonesia/5/05. In another embodiment, said M1 is from influenza strain A/Indonesia/5/05. In another embodiment, said HA and/or NA is from influenza strain A/Wisconsin/67/2005. In another embodiment, said non-avian influenza protein is from a virus, bacteria, fungus and/or parasite. For example, the non-avian influenza protein is a SARS virus S protein. In another embodiment, said non-avian protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein from an infective agent, wherein said HA and NA proteins are described above. In another embodiment, the antigenic formulation comprises a chimeric VLP comprising an influenza M1 protein comprising an Lysine at the second position of the M1 protein L domain. In another embodiment, said L domain comprises the sequence YKKL. In another embodiment of the invention, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent. In another embodiment, said infectious agent is from a virus, bacteria, fungus and/or parasite. In another embodiment, said non-avian influenza protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and or influenza NA fused to a protein from an infective agent. In another embodiment, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent.

Said formulations of the invention comprise a formulation comprising VLPs comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one protein from a non-avian influenza protein (e.g. a protein from an infectious agent described above) and a pharmaceutically acceptable carrier or excipient. Pharmaceutically acceptable carriers include but are not limited to saline, buffered saline, dextrose, water, glycerol, sterile isotonic aqueous buffer, and combinations thereof. A thorough discussion of pharmaceutically acceptable carriers, diluents, and other excipients is presented in Remington's Pharmaceutical Sciences (Mack Pub. Co. N.J. current edition). The formulation should suit the mode of administration. In another embodiment, the formulation is suitable for administration to humans, preferably is sterile, non-particulate, and/or non-pyrogenic.

The formulation, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. The formulation can be a solid form, such as a lyophilized powder suitable for reconstitution, a liquid solution, suspension, emulsion, tablet, pill, capsule, sustained release formulation, or powder. Oral formulation can include standard carriers such as pharmaceutical grades of mannitol, lactose, starch, magnesium stearate, sodium saccharine, cellulose, magnesium carbonate, etc.

The pharmaceutical formulation useful herein contain a pharmaceutically acceptable carrier, including any suitable diluent or excipient, which includes any pharmaceutical agent that does not itself induce the production of an immune response harmful to the vertebrate receiving the composition, and which may be administered without undue toxicity and a VLP of the invention. As used herein, the term “pharmaceutically acceptable” means being approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopia, European Pharmacopia, or other generally recognized pharmacopia for use in mammals, and more particularly in humans. These compositions can be useful as a vaccine and/or antigenic compositions for inducing a protective immune response in a vertebrate.

The invention comprises a vaccine comprising a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP comprises HA and/or NA from a non-avian influenza virus. In another embodiment, said HA or NA have hemagglutinin and neuraminidase activity, respectively. In another embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian HA and/or NA cytoplasmic region. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA are from influenza strain A/Indonesia/5/05. In another embodiment, said M1 is from influenza strain A/Indonesia/5/05. In another embodiment, said HA and/or NA is from influenza strain A/Wisconsin/67/2005. In another embodiment, said non-avian influenza protein is from a virus, bacteria, fungus and/or parasite. For example, the non-avian influenza protein is a SARS virus S protein. In another embodiment, said non-avian protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein from an infective agent, wherein said HA and NA proteins are described above. In another embodiment, the antigenic formulation comprises a chimeric VLP comprising an influenza M1 protein comprising an Lysine at the second position of the M1 protein L domain. In another embodiment, said L domain comprises the sequence YKKL. In another embodiment of the invention, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent. In another embodiment, said infectious agent is from a virus, bacteria, fungus and/or parasite. In another embodiment, said non-avian influenza protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and or influenza NA fused to a protein, or a portion thereof, from an infective agent. In another embodiment, said VLPs comprise more than one protein from an infectious agent.

The invention also provides for a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the vaccine formulations of the invention. In one embodiment, the kit comprises two containers, one containing VLPs and the other containing an adjuvant. In another embodiment, the kit comprises two containers, one containing freeze dried VLPs and the other containing a solution to resuspend said VLPs. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration.

The invention also provides that the VLP formulation be packaged in a hermetically sealed container such as an ampoule or sachette indicating the quantity of composition. In one embodiment, the VLP composition is supplied as a liquid, in another embodiment, as a dry sterilized lyophilized powder or water free concentrate in a hermetically sealed container and can be reconstituted, e.g., with water or saline, to the appropriate concentration for administration to a subject. In one embodiment, said container comprises at least about 50 μg/ml, more preferably at least about 100 μg/ml, at least about 200 μg/ml, at least 500 μg/ml, or at least 1 mg/ml of an antigen associated with VLPs of the invention. These doses may be measured as total VLPs or as μg of HA. The VLP composition should be administered within about 12 hours, preferably within about 6 hours, within about 5 hours, within about 3 hours, or within about 1 hour after being reconstituted from the lyophylized powder.

In an alternative embodiment, the VLP composition is supplied in liquid form in a hermetically sealed container indicating the quantity and concentration of the VLP composition. The liquid form of the VLP composition is supplied in a hermetically sealed container at least about 50 μg/ml, more preferably at least about 100 μg/ml, at least about 200 μg/ml, at least 500 μg/ml, or at least 1 mg/ml of an antigen associated with VLPs of the invention.

Generally, VLPs of the invention are administered in an effective amount or quantity (as defined above) sufficient to stimulate an immune response against one or more infectious agents. Preferably, administration of the VLP of the invention elicits immunity against an infectious agent. Typically, the dose can be adjusted within this range based on, e.g., age, physical condition, body weight, sex, diet, time of administration, and other clinical factors. The prophylactic vaccine formulation is systemically administered, e.g., by subcutaneous or intramuscular injection using a needle and syringe, or a needle-less injection device. Alternatively, the vaccine formulation is administered intranasally, either by drops, large particle aerosol (greater than about 10 microns), or spray into the upper respiratory tract. While any of the above routes of delivery results in an immune response, intranasal administration confers the added benefit of eliciting mucosal immunity at the site of entry of many viruses, including RSV and influenza.

Thus, the invention also comprises a method of formulating a vaccine or antigenic composition that induces immunity to an infection or at least one symptom thereof to a mammal, comprising adding to said formulation an effective dose of VLPs of the invention.

Methods of administering a composition comprising VLPs (vaccine and/or antigenic formulations) include, but are not limited to, parenteral administration (e.g., intradermal, intramuscular, intravenous and subcutaneous), epidural, and mucosal (e.g., intranasal and oral or pulmonary routes or by suppositories). In a specific embodiment, compositions of the present invention are administered intramuscularly, intravenously, subcutaneously, transdermally or intradermally. The compositions may be administered by any convenient route, for example by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucous, colon, conjunctiva, nasopharynx, oropharynx, vagina, urethra, urinary bladder and intestinal mucosa, etc.) and may be administered together with other biologically active agents. In some embodiments, intranasal or other mucosal routes of administration of a composition comprising VLPs of the invention may induce an antibody or other immune response that is substantially higher than other routes of administration. In another embodiment, intranasal or other mucosal routes of administration of a composition comprising VLPs of the invention may induce an antibody or other immune response that will induce cross protection against other strains or organisms that cause infection. For example, a VLP comprising influenza protein, when administered to a vertebrate, can induce cross protection against several influenza strains. Administration can be systemic or local.

In yet another embodiment, the vaccine and/or antigenic formulation is administered in such a manner as to target mucosal tissues in order to elicit an immune response at the site of immunization. For example, mucosal tissues such as gut associated lymphoid tissue (GALT) can be targeted for immunization by using oral administration of compositions which contain adjuvants with particular mucosal targeting properties. Additional mucosal tissues can also be targeted, such as nasopharyngeal lymphoid tissue (NALT) and bronchial-associated lymphoid tissue (BALT).

Vaccines and/or antigenic formulations of the invention may also be administered on a dosage schedule, for example, an initial administration of the vaccine composition with subsequent booster administrations. In particular embodiments, a second dose of the composition is administered anywhere from two weeks to one year, preferably from about 1, about 2, about 3, about 4, about 5 to about 6 months, after the initial administration. Additionally, a third dose may be administered after the second dose and from about three months to about two years, or even longer, preferably about 4, about 5, or about 6 months, or about 7 months to about one year after the initial administration. The third dose may be optionally administered when no or low levels of specific immunoglobulins are detected in the serum and/or urine or mucosal secretions of the subject after the second dose. In a preferred embodiment, a second dose is administered about one month after the first administration and a third dose is administered about six months after the first administration. In another embodiment, the second dose is administered about six months after the first administration. In another embodiment, said VLPs of the invention can be administered as part of a combination therapy. For example, VLPs of the invention can be formulated with other immunogenic compositions, antivirals (e.g. amantadine, rimantidine, zanamivir, and osteltamivir) and/or antibiotics.

The dosage of the pharmaceutical formulation can be determined readily by the skilled artisan, for example, by first identifying doses effective to elicit a prophylactic or therapeutic immune response, e.g., by measuring the serum titer of virus specific immunoglobulins or by measuring the inhibitory ratio of antibodies in serum samples, or urine samples, or mucosal secretions. Said dosages can be determined from animal studies. A non-limiting list of animals used to study the efficacy of vaccines include the guinea pig, hamster, ferrets, chinchilla, mouse and cotton rat. Most animals are not natural hosts to infectious agents but can still serve in studies of various aspects of the disease. For example, any of the above animals can be dosed with a vaccine candidate, e.g. VLPs of the invention, to partially characterize the immune response induced, and/or to determine if any neutralizing antibodies have been produced. For example, many studies have been conducted in the mouse model because mice are small size and their low cost allows researchers to conduct studies on a larger scale. Nevertheless, the mouse's small size also increases the difficulty of readily observing any clinical signs of disease and the mouse is not a predictive model for disease in humans.

There has been extensive use of ferrets for studying various aspects of human influenza viral infection and its course of action. The development of many of the contemporary concepts of immunity to the influenza virus would have been impossible without the use of the ferret (Maher et al, 2004). Ferrets have proven to be a good model for studying influenza for several reasons: influenza infection in the ferret closely resembles that in humans with respect to clinical signs, pathogenesis, and immunity; types A and B of human influenza virus naturally infect the ferret, thus providing an opportunity to study a completely controlled population in which to observe the interplay of transmission of infection, illness, and sequence variation of amino acids in the glycoproteins of the influenza virus; and ferrets have other physical characteristics that make it an ideal model for deciphering the manifestations of the disease. For example, ferrets and humans show very similar clinical signs of influenza infection that seem to depend on the age of the host, the strain of the virus, environmental conditions, the degree of secondary bacterial infection, and many other variables. Thus, one skilled in the art can more easily correlate the efficacy of an influenza vaccine and dosage regiments from a ferret model to humans as compared to a mouse or any other model described above.

In addition, human clinical studies can be performed to determine the preferred effective dose for humans by a skilled artisan. Such clinical studies are routine and well known in the art. The precise dose to be employed will also depend on the route of administration. Effective doses may be extrapolated from dose-response curves derived from in vitro or animal test systems.

As also well known in the art, the immunogenicity of a particular composition can be enhanced by the use of non-specific stimulators of the immune response, known as adjuvants. Adjuvants have been used experimentally to promote a generalized increase in immunity against unknown antigens (e.g., U.S. Pat. No. 4,877,611) Immunization protocols have used adjuvants to stimulate responses for many years, and as such, adjuvants are well known to one of ordinary skill in the art. Some adjuvants affect the way in which antigens are presented. For example, the immune response is increased when protein antigens are precipitated by alum. Emulsification of antigens also prolongs the duration of antigen presentation. The inclusion of any adjuvant described in Vogel et al., “A Compendium of Vaccine Adjuvants and Excipients (2^(nd) Edition),” herein incorporated by reference in its entirety for all purposes, is envisioned within the scope of this invention.

Exemplary, adjuvants include complete Freund's adjuvant (a non-specific stimulator of the immune response containing killed Mycobacterium tuberculosis), incomplete Freund's adjuvants and aluminum hydroxide adjuvant. Other adjuvants comprise GMCSP, BCG, aluminum hydroxide, MDP compounds, such as thur-MDP and nor-MDP, CGP (MTP-PE), lipid A, and monophosphoryl lipid A (MPL). RIBI, which contains three components extracted from bacteria, MPL, trehalose dimycolate (TDM) and cell wall skeleton (CWS) in a 2% squalene/Tween 80 emulsion also is contemplated. MF-59, Novasomes®, MHC antigens may also be used.

In one embodiment of the invention, the adjuvant is a paucilamellar lipid vesicle having about two to ten bilayers arranged in the form of substantially spherical shells separated by aqueous layers surrounding a large amorphous central cavity free of lipid bilayers. Paucilamellar lipid vesicles may act to stimulate the immune response several ways, as non-specific stimulators, as carriers for the antigen, as carriers of additional adjuvants, and combinations thereof. Paucilamellar lipid vesicles act as non-specific immune stimulators when, for example, a vaccine is prepared by intermixing the antigen with the preformed vesicles such that the antigen remains extracellular to the vesicles. By encapsulating an antigen within the central cavity of the vesicle, the vesicle acts both as an immune stimulator and as a carrier for the antigen. In another embodiment, the vesicles are primarily made of nonphospholipid vesicles. In another embodiment, the vesicles are Novasomes®. Novasomes® are paucilamellar nonphospholipid vesicles ranging from about 100 nm to about 500 nm. They comprise Brij 72, cholesterol, oleic acid and squalene. Novasomes® have been shown to be an effective adjuvant for influenza antigens (see, U.S. Pat. Nos. 5,629,021, 6,387,373, and 4,911,928, herein incorporated by reference in their entireties for all purposes).

In one aspect, an adjuvant effect is achieved by use of an agent, such as alum, used in about 0.05 to about 0.1% solution in phosphate buffered saline. Alternatively, the VLPs can be made as an admixture with synthetic polymers of sugars (Carbopol®) used as an about 0.25% solution. Some adjuvants, for example, certain organic molecules obtained from bacteria; act on the host rather than on the antigen. An example is muramyl dipeptide (N-acetylmuramyl-L-alanyl-D-isoglutamine [MDP]), a bacterial peptidoglycan. In other embodiments, hemocyanins and hemoerythrins may also be used with VLPs of the invention. The use of hemocyanin from keyhole limpet (KLH) is preferred in certain embodiments, although other molluscan and arthropod hemocyanins and hemoerythrins may be employed.

Various polysaccharide adjuvants may also be used. For example, the use of various pneumococcal polysaccharide adjuvants on the antibody responses of mice has been described (Yin et al., 1989). The doses that produce optimal responses, or that otherwise do not produce suppression, should be employed as indicated (Yin et al., 1989). Polyamine varieties of polysaccharides are particularly preferred, such as chitin and chitosan, including deacetylated chitin. In another embodiment, a lipophilic disaccharide-tripeptide derivative of muramyl dipeptide which is described for use in artificial liposomes formed from phosphatidyl choline and phosphatidyl glycerol.

Amphipathic and surface active agents, e.g., saponin and derivatives such as QS21 (Cambridge Biotech), form yet another group of adjuvants for use with the VLPs of the invention. Nonionic block copolymer surfactants (Rabinovich et al., 1994) may also be employed. Oligonucleotides are another useful group of adjuvants (Yamamoto et al., 1988). Quil A and lentinen are other adjuvants that may be used in certain embodiments of the present invention.

Another group of adjuvants are the detoxified endotoxins, such as the refined detoxified endotoxin of U.S. Pat. No. 4,866,034. These refined detoxified endotoxins are effective in producing adjuvant responses in vertebrates. Of course, the detoxified endotoxins may be combined with other adjuvants to prepare multi-adjuvant formulation. For example, combination of detoxified endotoxins with trehalose dimycolate is particularly contemplated, as described in U.S. Pat. No. 4,435,386. Combinations of detoxified endotoxins with trehalose dimycolate and endotoxic glycolipids is also contemplated (U.S. Pat. No. 4,505,899), as is combination of detoxified endotoxins with cell wall skeleton (CWS) or CWS and trehalose dimycolate, as described in U.S. Pat. Nos. 4,436,727, 4,436,728 and 4,505,900. Combinations of just CWS and trehalose dimycolate, without detoxified endotoxins, is also envisioned to be useful, as described in U.S. Pat. No. 4,520,019.

Those of skill in the art will know the different kinds of adjuvants that can be conjugated to vaccines in accordance with this invention and these include alkyl lysophosphilipids (ALP); BCG; and biotin (including biotinylated derivatives) among others. Certain adjuvants particularly contemplated for use are the teichoic acids from Gram-cells. These include the lipoteichoic acids (LTA), ribitol teichoic acids (RTA) and glycerol teichoic acid (GTA). Active forms of their synthetic counterparts may also be employed in connection with the invention (Takada et al., 1995).

Various adjuvants, even those that are not commonly used in humans, may still be employed in other vertebrates, where, for example, one desires to raise antibodies or to subsequently obtain activated T cells. The toxicity or other adverse effects that may result from either the adjuvant or the cells, e.g., as may occur using non-irradiated tumor cells, is irrelevant in such circumstances.

Another method of inducing an immune response can be accomplished by formulating the VLPs of the invention with “immune stimulators.” These are the body's own chemical messengers (cytokines) to increase the immune system's response Immune stimulators include, but not limited to, various cytokines, lymphokines and chemokines with immunostimulatory, immunopotentiating, and pro-inflammatory activities, such as interleukins (e.g., IL-1, IL-2, IL-3, IL-4, IL-12, IL-13); growth factors (e.g., granulocyte-macrophage (GM)-colony stimulating factor (CSF)); and other immunostimulatory molecules, such as macrophage inflammatory factor, Flt3 ligand, B7.1; B7.2, etc. The immunostimulatory molecules can be administered in the same formulation as the RSV VLPs, or can be administered separately. Either the protein or an expression vector encoding the protein can be administered to produce an immunostimulatory effect. Thus in one embodiment, the invention comprises antigenic and vaccine formulations comprising an adjuvant and/or an immune stimulator.

Thus, one embodiment of the invention comprises a formulation comprising a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein (or at least one protein from an infectious agent) and adjuvant and/or an immune stimulator. In another embodiment, said adjuvant are Novasomes®. In another embodiment, said formulation is suitable for human administration. In another embodiment, the formulation is administered to a vertebrate orally, intradermally, intranasally, intramuscularly, intraperitoneally, intravenously or subcutaneously. In another embodiment, different chimeric VLPs are blended together to create a multivalent formulation. These VLPs may comprise VLPs HA and/or NA from different strains of influenza virus (e.g. influenza A and/or influenza B) or protein from different infectious agents (e.g. RSV, coronavirus, HIV).

While stimulation of immunity with a single dose is preferred, additional dosages can be administered by the same or different route to achieve the desired effect. In neonates and infants, for example, multiple administrations may be required to elicit sufficient levels of immunity. Administration can continue at intervals throughout childhood, as necessary to maintain sufficient levels of protection against infections. Similarly, adults who are particularly susceptible to repeated or serious infections, such as, for example, health care workers, day care workers, family members of young children, the elderly, and individuals with compromised cardiopulmonary function may require multiple immunizations to establish and/or maintain protective immune responses. Levels of induced immunity can be monitored, for example, by measuring amounts of neutralizing secretory and serum antibodies, and dosages adjusted or vaccinations repeated as necessary to elicit and maintain desired levels of protection. In one embodiment, doses are administered at least 2 weeks apart, at least 3 weeks apart, at least 4 weeks apart, at least 5 weeks apart or at least 6 weeks apart.

Methods of Stimulating an Immune Response

As mentioned above, the VLPs of the invention are useful for preparing compositions that stimulate an immune response that confers immunity to infectious agents. Both mucosal and cellular immunity may contribute to immunity to infectious agents and disease. Antibodies secreted locally in the upper respiratory tract are a major factor in resistance to natural infection. Secretory immunoglobulin A (sIgA) is involved in protection of the upper respiratory tract and serum IgG in protection of the lower respiratory tract. The immune response induced by an infection protects against reinfection with the same virus or an antigenically similar viral strain. For example, influenza undergoes frequent and unpredictable changes; therefore, after natural infection, the effective period of protection provided by the host's immunity may only be a few years against the new strains of virus circulating in the community.

VLPs of the invention can induce immune responses in a vertebrate (e.g. a human) when administered to said vertebrate. The immunity results from an immune response against VLPs of the invention that protects or ameliorates infection or at least reduces a symptom of infection in said vertebrate. In some instances, if the said vertebrate is infected, said infection will be asymptomatic. The response may be not a fully protective response. In this case, if said vertebrate is infected with an infectious agent, the vertebrate will experience reduced symptoms or a shorter duration of symptoms compared to a non-immunized vertebrate.

The invention comprises methods of inducing immune response in a vertebrate comprising administering to said vertebrate the VLP of the present invention comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said immune response is a humoral immune response. In another embodiment, said immune response is a cellular immune response. In another embodiment, said non-avian influenza protein is HA and/or NA from a non-avian influenza virus. In another embodiment, said non-avian influenza protein is a seasonal influenza protein. In another embodiment, said HA or NA has hemagglutinin or neuraminidase activity, respectively. In one embodiment, said HA and/or NA are chimeric proteins. In another embodiment, said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of the avian HA and/or NA cytoplasmic region. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA transmembrane and/or cytoplasmic-terminal domains are from influenza strain A/Indonesia/5/05. In another embodiment, said M1 is from influenza strain A/Indonesia/5/05. In another embodiment, said HA and/or NA is from influenza strain A/Wisconsin/67/2005. In another embodiment, the chimeric VLP comprises an influenza M1 protein comprising an lysine at the second position of the M1 protein putative L-domain. In another embodiment, said putative L-domain comprises the sequence YKKL. In another embodiment, said VLPs comprise more than one protein from an infectious agent. In another embodiment, said chimeric proteins comprise a fusion between the influenza HA with the protein, or a portion thereof, from an infectious agent. The VLPs may comprise additional proteins and/or protein contaminates in negligible concentrations. In another embodiment, the VLP comprises a M1 protein and at least one chimeric protein, wherein said VLP contains a M1 protein and at least one chimeric protein and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional fragments of the M1 protein and the chimeric protein. In one embodiment, said method comprises administering to said vertebrate the VLP orally, intradermally, intranasally, intramuscularly, intraperitoneally, intravenously, or subcutaneously. In one embodiment, at least two effective doses of the vaccine are administered. In another embodiment, the doses are administered at least 2 weeks apart, at least 3 weeks apart, at least 4 weeks apart, at least 5 weeks apart or at least 6 weeks apart. In another embodiment, said vaccine further comprises an adjuvant or immune stimulator.

In another embodiment, said non-avian influenza protein is from a virus, bacteria, fungus and/or parasite. For example, the non-avian influenza protein is a SARS virus S protein. In another embodiment, said non-avian protein is a chimeric protein comprising the transmembrane domain and/or cytoplasmic tail of influenza HA and/or influenza NA fused to a protein, or a portion thereof, from an infective agent. In another embodiment, said chimeric protein comprise at least one external domain (ectodomain) of influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic-terminal domains of a heterologous HA and/or NA. In another embodiment, said heterologous transmembrane and/or cytoplasmic-terminal domains HA and/or NA is from a pandemic, seasonal and/or avian influenza virus. In another embodiment, said heterologous transmembrane and/or cytoplasmic-terminal domains HA and/or NA is from a pandemic, seasonal and/or avian influenza virus and a NA from a pandemic, seasonal and/or avian influenza virus, wherein said HA is selected from the group consisting of H1, H2, H3, H4, H5, H6, H,7 H8, H9, H10, H11, H12, H13, H14, H15 and H16 and said NA is selected from the group consisting of N1, N2, N3, N4, N5, N6, N7, N8 and N9. In another embodiment, said influenza HA and/or NA are from a seasonal influenza strain A/Wisconsin/67/2005 and HA and/or NA transmembrane and/or cytoplasmic-terminal domains are from an avian influenza strain. In another embodiment, said non-avian influenza HA and/or NA are from influenza strain A/Fujian/411/02 and HA and/or NA transmembrane and/or cytoplasmic-terminal domains are from an avian influenza strain. Said HA and/or NA transmembrane and/or cytoplasmic-terminal domains from avian influenza can be derived from the group consisting of influenza virus H9N2 and influenza virus H5N1.

As used herein, an “antibody” is a protein comprising one or more polypeptides substantially or partially encoded by immunoglobulin genes or fragments of immunoglobulin genes. The recognized immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon, and mu constant region genes, as well as myriad immunoglobulin variable region genes. Light chains are classified as either kappa or lambda. Heavy chains are classified as γ, μ, α, δ, or ε, which in turn define the immunoglobulin classes, IgG, IgM, IgA, IgD, and IgE, respectively. A typical immunoglobulin (antibody) structural unit comprises a tetramer. Each tetramer is composed of two identical pairs of polypeptide chains, each pair having one “light” (about 25 kD) and one “heavy” chain (about 50-70 kD). The N-terminus of each chain defines a variable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. Antibodies exist as intact immunoglobulins or as a number of well-characterized fragments produced by digestion with various peptidases.

In another embodiment, the invention comprises a method of inducing a protective cellular response to an infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of VLPs of the invention, wherein said VLPs comprise an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. Cell-mediated immunity also plays a role in recovery from infection and may prevent additional complication and contribute to long term immunity.

As mentioned above, the VLPs of the invention can prevent or reduce at least one symptom of an infection in a subject when administered to said subject. Most symptoms of most infections are well known in the art. Thus, the method of the invention comprises the prevention or reduction of at least one symptom associated with an infection. A reduction in a symptom may be determined subjectively or objectively, e.g., self assessment by a subject, by a clinician's assessment or by conducting an appropriate assay or measurement (e.g. body temperature), including, e.g., a quality of life assessment, a slowed progression of an infection or additional symptoms, reduced severity of symptoms, or suitable assays (e.g. antibody titer and/or T-cell activation assay). The objective assessment comprises both animal and human assessments.

The invention comprises a method of preventing and/or reducing an infection or symptom thereof, comprising administering to said vertebrate a chimeric VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment said infection is a viral infection. In another embodiment, said viral infection is an influenza infection.

A strategy for the control of infectious diseases during an outbreak, e.g. influenza, is the universal vaccination of healthy individuals, including children. For example, vaccination with current influenza vaccines of approximately 80% of schoolchildren in a community has decreased respiratory illnesses in adults and excess deaths in the elderly (Reichert et al., 2001). This concept is known as community immunity or “herd immunity” and is thought to play an important part of protecting the community against diseases. Because vaccinated people have antibodies that neutralize and infectious agent, e.g. influenza virus, they are much less likely to transmit said agent to other people. Thus, even people who have not been vaccinated (and those whose vaccinations have become weakened or whose vaccines are not fully effective) often can be shielded by the herd immunity because vaccinated people around them are not getting sick. Herd immunity is more effective as the percentage of people vaccinated increases. It is thought that approximately 95% of the people in the community must be protected by a vaccine to achieve herd immunity. People who are not immunized increase the chance that they and others will get the disease.

Thus, the invention also comprises a method of reducing the severity of an infectious disease in a population, comprising administering a VLP comprising an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein to enough individuals in said population in order to prevent or decrease the chance of transmission to another individual in said population. In one embodiment, said VLP consists essentially of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said VLP consists of an influenza M1 protein comprising a K¹⁰¹ residue, such as an avian influenza M1 protein, and at least one non-avian influenza protein. In another embodiment, said infectious disease is caused by influenza virus. The invention also encompasses a method of inducing immunity to an infectious agent to a population or a community in order to reduce the incidence of infections among immunocompromised individuals or non-vaccinated individual buy administering VLPs of the invention to a population in a community. In one embodiment, most school-aged children are immunized by administering the VLPs of the invention. In another embodiment, most healthy individuals in a community to are immunized by administering the VLPs of the invention. In another embodiment, VLPs of the invention are part of a “dynamic vaccination” strategy. Dynamic vaccination is the steady production of a low-efficacy vaccine that is related to an emerging pandemic strain, but due to an antigenic drift may not provide complete protection in a mammal (see Germann et al., 2006).

Method of Stimulating an Anti-Influenza Immune Response

In one embodiment, the invention comprises a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP. In another embodiment, said induction of substantial immunity reduces duration of influenza symptoms. In another embodiment, a method to induce substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP comprises influenza HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In one embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In one embodiment, said influenza M1 protein is an avian influenza M1 protein. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists essentially of influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In one embodiment, said influenza M1 protein is an avian influenza M1 protein. Said VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists of influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In one embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator.

Recently there has been a concerted effort to create a vaccine against avian influenza virus that has the potential to create a pandemic. That is because a number of avian influenza viruses have crossed the species barrier and directly infected humans resulting in illness and, in some cases, death. These viruses were H5N1, H9N2 and H7N7 (Cox et al., 2004). A recent study examined the potential of using inactivated H5N1 influenza virus as a vaccine. The formulation of the vaccine was similar to the licensed inactivated vaccines currently licensed for marketing. The study concluded that using inactivated H5N1 virus did induce an immune response in humans, however the dose given was very high (90 μg of avian influenza compared to 15 μg of the licensed vaccine) (Treanor et al., 2006). This high amount of avian influenza antigen is impractical for a worldwide vaccination campaign. As illustrated below, the VLPs of the invention induces an immune response in a vertebrate when administered to said vertebrate.

Thus, the invention encompasses a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an avian influenza VLP. In another embodiment, said induction of substantial immunity reduces duration of influenza symptoms. In another embodiment, said induction of immunity is from administering at least 0.2 μg of avian HA in VLPs of the invention. In another embodiment, said induction of immunity is from administering about 0.2 μg of avian HA to about 15 μg of avian HA in VLPs of the invention. In another embodiment, said induction of immunity is from administering about 15 μg of avian HA to about 45 μg of avian HA in VLPs of the invention. In another embodiment, said induction of immunity is from administering about 45 μg of avian HA to about 135 μg of avian HA in VLPs of the invention. In another embodiment, said induction of immunity is from administering about 10 μg, about 20 μg, about 30 μg, about 40 μg, about 45 μg, about 50 μg, about 60 μg, about 70 μg, about 80 μg, about 90 μg, about 100 μg, about 110 μg, about 120 μg, about 130 μg, about 140 μg, about 150 μg or higher. Administration may be in one or more doses, but may be advantageously in a single dose. In another embodiment, said VLP avian HA is derived from avian influenza H5N1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein.

In another embodiment, the invention comprises a method of inducing substantial immunity to avian influenza virus infection or at least one symptom thereof in a subject comprising administering at least one effective dose of an avian influenza VLP, wherein said VLP comprises an avian influenza HA, NA and M1. In another embodiment, said avian influenza VLP comprises avian influenza proteins, wherein said avian influenza proteins consist of HA, NA and M1 proteins. In one embodiment, said avian influenza M1 protein comprises a K¹⁰¹ residue.

These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc. but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, said method of inducing substantial immunity to avian influenza virus infection or at least one symptom thereof in a subject comprises administering at least one effective dose of an avian influenza VLP, wherein said VLP consists essentially of avian influenza HA, NA and M1. In one embodiment, said avian influenza M1 protein comprises a K¹⁰¹ residue.

Said VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, a method to induce substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists of avian influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue.

In another embodiment, said avian influenza HA and NA are H5N1, respectively. In another embodiment, said avian influenza HA and NA are H9N2, respectively. In another embodiment, said avian influenza HA and NA are H7N7, respectively. In another embodiment, said avian influenza HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator.

In another embodiment, said avian influenza VLPs will induce an immune response in a vertebrate that is about 2 fold, about 4 fold, about 8 fold, about 16 fold, about 32 fold about 64 fold, about 128 fold increase (or higher) more potent than a similar avian influenza antigens formulated similarly to the licensed inactivated vaccines currently licensed for marketing. Current formulations comprise whole inactivated virus (e.g. formaldehyde treated), split virus (chemically disrupted), and subunit (purified glycoprotein) vaccines. Methods for determining potency for a vaccine are known and routine in the art. For example, microneutralization assays and hemagglutination inhibition assays can be performed to determine potency of an avian VLP vaccine compared to avian influenza antigens formulated similar to the licensed inactivated vaccines currently licensed for marketing. In one embodiment, said increase in potency is realized when about 0.2 μg, about 0.4 μg, about 0.6 μg about 0.8 μg, about 1 μg, about 2 μg, about 3 μg, about 4 μg, about 5 μg, about 6 μg, about 7 μg, about 9 μg, about 10 μg, about 15 μg, about 20 μg, about 25 μg, about 30 μg, about 35 μg, 40 μg, about 45 μg, about 50 μg, about 60 μg, about 70 μg, about 80 μg, about 90 μg, about 100 μg, about 110 μg, about 120 μg, about 130 μg, about 140 μg, about 150 μg or higher of VLPs and the antigen formulated similarly to the inactivated vaccines currently licensed for marketing is administered to a vertebrate (i.e. equivalent amounts of HA and/or NA in a VLP with equivalent amounts of HA and/or NA formulated in similarly to the licensed inactivated vaccines and/or any other antigen) Amounts can be measured according to HA content. For example, 1 μg of a VLP of the invention is about 1 μg of HA in a solution of VLPs comprising HA or may be measured by weight of VLPs.

Seasonal influenza vaccines are administered to humans every year to reduce the incidence of influenza cases every year. At present, there are two subtypes of influenza A and influenza B circulating in the United States. Current vaccines are, therefore, trivalent to provide protection against the strains currently circulating. Each year a different stain or variation of an influenza viral changes. Thus, for most years a new vaccine composition is manufactured and administered. Inactivated vaccines are produced by propagation of the virus in embryonated hens' eggs. The allantoic fluid is harvested, and the virus is concentrated and purified, then inactivated. Thus, the current licensed influenza virus vaccines may contain trace amounts of residual egg proteins and, therefore, should not be administered to persons who have anaphylactic hypersensitivity to eggs. In addition, supplies of eggs must be organized and strains for vaccine production must be selected months in advance of the next influenza season, thus limiting the flexibility of this approach and often resulting in delays and shortages in production and distribution. In addition, some influenza strains do not replicate well in embryonated chicken eggs which may limit the influenza strains which can be grown and formulated into vaccines.

As mentioned above, VLP of the invention do not require eggs for production. These VLPs are made via a cell culture system. Thus, the invention encompasses a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of a seasonal influenza VLP. A discussed above, seasonal influenza virus refers to the influenza viral strains that has been determined to be passing within the human population for a given influenza season based on the epidemiological surveys by National Influenza Centers worldwide. Said studies and some isolated influenza viruses are sent to one of four World Health Organization (WHO) reference laboratories, one of which is located at the Centers for Disease Control and Prevention (CDC) in Atlanta, for detailed testing. These laboratories test how well antibodies made to the current vaccine react to the circulating virus and new flu viruses. This information, along with information about flu activity, is summarized and presented to an advisory committee of the U.S. Food and Drug Administration (FDA) and at a WHO meeting. These meetings result in the selection of three viruses (two subtypes of influenza A viruses and one influenza B virus) to go into flu vaccines for the following fall and winter. The selection occurs in February for the northern hemisphere and in September for the southern hemisphere. Usually, one or two of the three virus strains in the vaccine changes each year. In another embodiment, said induction of substantial immunity reduces duration of influenza symptoms.

In another embodiment, the invention comprises a method of inducing substantial immunity to a seasonal influenza virus infection or at least one symptom thereof in a subject comprising administering at least one effective dose of a seasonal influenza VLP, wherein said VLP comprises a seasonal influenza HA, NA and M1. In one embodiment, said seasonal influenza M1 protein has been mutated to comprise a K¹⁰¹ residue.

In another embodiment, said seasonal influenza VLP comprises seasonal influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. In one embodiment, said seasonal influenza M1 protein has been mutated to comprise a K¹⁰¹ residue. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc. but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, said method of inducing substantial immunity to seasonal influenza virus infection or at least one symptom thereof in a subject comprises administering at least one effective dose of a seasonal influenza VLP, wherein said VLP consists essentially of seasonal influenza HA, NA and M1. In one embodiment, said seasonal influenza M1 protein has been mutated to comprise a K¹⁰¹ residue. Said VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, a method to induce substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists of seasonal influenza HA, NA and M1. In one embodiment, said seasonal influenza M1 protein has been mutated to comprise a K¹⁰¹ residue. In another embodiment, said avian influenza HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator.

Generally, seasonal influenza VLPs of the invention are administered in a quantity sufficient to stimulate substantial immunity for one or more strains of seasonal influenza virus. In one embodiment, the VLPs are blended together with other VLPs comprising different influenza subtypes proteins (as listed above). In another embodiment, the formulation is a trivalent formulation which comprises a mixture of VLPs with seasonal influenza HA and/or NA proteins from at least two influenza A and/or one at least one B subtype. In another embodiment, said B subtype is produced by the same method as described above. In another embodiment, a multivalent formulation comprises one or more of the VLP of the invention as described above.

In another embodiment, VLPs of the invention (avian or seasonal VLPs) may elicit an immune response that will provide protection against more than one strain of influenza virus. This cross-protection of a vertebrate with an influenza VLP constructed from a particular strain, of a particular subgroup, may induce cross-protection against influenza virus of different strains and/or subgroups. The examples below show that VLPs of the invention are capable of inducing cross reactivity with different strains and/or subgroups.

The humoral immune system produces antibodies against different influenza antigens, of which the HA-specific antibody is the most important for neutralization of the virus and thus prevention of illness. The NA-specific antibodies are less effective in preventing infection, but they lessen the release of virus from infected cells. The mucosal tissues are the main portal entry of many pathogens, including influenza, and the mucosal immune system provides the first line of defense against infection apart from innate immunity. SIgA and, to some extent, IgM are the major neutralizing antibodies directed against mucosal pathogens preventing pathogen entry and can function intracellularly to inhibit replication of virus. Nasal secretions contain neutralizing antibodies particularly to influenza HA and NA, which are primarily of the IgA isotype and are produced locally. During primary infection, all three major Ig classes (IgG, IgA and IgM) specific to HA can be detected by enzyme-linked immunosorbent assay in nasal washings, although IgA and IgM are more frequently detected than IgG. Both IgA and, to some extent, IgM are actively secreted locally, whereas IgG is derived as a serum secretion. In subjects who have a local IgA response, a serum IgA response also is observed. The local IgA response stimulated by natural infection lasts for at least 3-5 months, and influenza-specific, IgA-committed memory cells can be detected locally. IgA also is the predominant Ig isotype in local secretions after secondary infection, and an IgA response is detected in the serum upon subsequent infection. The presence of locally produced neutralizing antibodies induced by live virus vaccine correlates with resistance to infection and illness after challenge with wild-type virus.

Resistance to influenza infection or illness is correlated with the level of local and/or serum antibody to HA and NA. Serum anti-HA antibodies are the most commonly measured correlate of protection against influenza (Cox et al., 1999). A protective serum antibody (haemagglutination inhibition (HI) titer ≧40) response can be detected in approximately 80% of subjects after natural influenza infection. B cells producing all three major Ig classes are present in the peripheral blood in normal subjects (Cox et al., 1994) and individuals undergoing influenza infection. In humans, serum antibodies play a role in both resistance to and recovery from influenza infection. The level of serum antibody to HA and NA in humans can be correlated with resistance to illness following experimental infection and natural infection. During primary infection, the three major Ig classes can be detected within 10-14 days. IgA and IgM levels peak after 2 weeks and then begin to decline, whereas the level of IgG peaks at 4-6 weeks. Whereas IgG and IgM are dominant in the primary response, IgG and IgA predominate in the secondary immune response.

Thus, the invention encompasses a method of inducing a substantially protective antibody response to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP. In another embodiment, said induction of substantially protective antibody response reduces duration of influenza symptoms. In another embodiment, a method to induce substantially protective antibody response to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP comprises influenza HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein.

In another embodiment, the invention comprises a method of inducing substantially protective antibody response to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists essentially of influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. Said VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment, a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists of influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, said influenza HA, NA and M1 is derived from seasonal influenza and/or avian influenza. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator.

As used herein, an “antibody” is a protein comprising one or more polypeptides substantially or partially encoded by immunoglobulin genes or fragments of immunoglobulin genes. The recognized immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon and mu constant region genes, as well as myriad immunoglobulin variable region genes. Light chains are classified as either kappa or lambda. Heavy chains are classified as gamma, mu, alpha, delta, or epsilon, which in turn define the immunoglobulin classes, IgG, IgM, IgA, IgD and IgE, respectively. A typical immunoglobulin (antibody) structural unit comprises a tetramer. Each tetramer is composed of two identical pairs of polypeptide chains, each pair having one “light” (about 25 kD) and one “heavy” chain (about 50-70 kD). The N-terminus of each chain defines a variable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. Antibodies exist as intact immunoglobulins or as a number of well-characterized fragments produced by digestion with various peptidases.

Cell-mediated immunity also plays a role in recovery from influenza infection and may prevent influenza-associated complications. Influenza-specific cellular lymphocytes have been detected in the blood and the lower respiratory tract secretions of infected subjects. Cytolysis of influenza-infected cells is mediated by CTLs in concert with influenza-specific antibodies and complement. The primary cytotoxic response is detectable in blood after 6-14 days and disappears by day 21 in infected or vaccinated individuals (Ennis et al., 1981). Influenza-specific CTLs exhibit cross-reactive specificities in in vitro cultures; thus, they lyse cells infected with the same type of influenza but not with other types (e.g. influenza A but not influenza B virus). CTLs that recognize the internal nonglycosylated proteins, M, NP and PB2 have been isolated (Fleischer et al., 1985). The CTL response is cross-reactive between influenza A strains (Gerhard et al., 2001) and is important in minimizing viral spread in combination with antibody (Nguyen et al., 2001).

Cell-mediated immunity also plays a role in recovery from influenza infection and may prevent influenza-associated complications. Influenza-specific cellular lymphocytes have been detected in the blood and the lower respiratory tract secretions of infected subjects. Cytolysis of influenza-infected cells is mediated by CTLs in concert with influenza-specific antibodies and complement. The primary cytotoxic response is detectable in blood after 6-14 days and disappears by day 21 in infected or vaccinated individuals (Ennis et al., 1981). Influenza-specific CTLs exhibit cross-reactive specificities in in vitro cultures; thus, they lyse cells infected with the same type of influenza but not with other types (e.g. influenza A but not influenza B virus). CTLs that recognize the internal nonglycosylated proteins, M, NP and PB2 have been isolated (Fleischer et al., (1985). The CTL response is cross-reactive between influenza A strains (Gerhard et al., 2001) and is important in minimizing viral spread in combination with antibody (Nguyen et al., 2001).

Thus, the invention encompasses a method of inducing a substantially protective cellular immune response to influenza virus infection or at least one symptom thereof in a subject, comprising administering at least one effective dose of an influenza VLP. In another embodiment, a method of inducing substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises administering at least one effective dose of an influenza VLP, wherein said VLP consists of influenza HA, NA and M1. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, said influenza VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc. but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In another embodiment wherein said influenza HA, NA and M1 is derived from seasonal influenza and/or avian influenza virus. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator.

As mentioned above, the VLPs of the invention (e.g. avian and/or seasonal influenza VLPs) prevent or reduce at least one symptom of influenza infection in a subject. Symptoms of influenza are well known in the art. They include fever, myalgia, headache, severe malaise, nonproductive cough, sore throat, weight loss and rhinitis. Thus, the method of the invention comprises the prevention or reduction of at least one symptom associated with influenza viral infection. A reduction in a symptom may be determined subjectively or objectively, e.g., self assessment by a subject, by a clinician's assessment or by conducting an appropriate assay or measurement (e.g. body temperature), including, e.g., a quality of life assessment, a slowed progression of an influenza infection or additional symptoms, a reduced severity of a influenza symptoms or a suitable assays (e.g. antibody titer and/or T-cell activation assay). The objective assessment comprises both animal and human assessments.

The principal strategy advocated by the Advisory Committee on Immunization Practices (ACIP) for control of influenza has been the vaccination of persons at risk for serious complications from influenza, in particular, people ≧65 years old. Yearly influenza epidemics, however, continue unabated and are responsible for significant health and financial burden to our society (Glaser et al., 1996). In the last 20 years (1976-1999), a significant increase has occurred in influenza-associated all cause excess deaths. From 1990 to 1999, the annual number of influenza-associated all cause deaths exceeded 50,000 (Thompson et al., 2003). Despite the increase in vaccine coverage of people ≧65 years to 65% during the last decade, a corresponding reduction in influenza-associated all cause excess deaths has not been observed.

Thus, another strategy for the prevention and control of influenza is universal vaccination of healthy children and individuals. Children have high rates of infection, medically attended illness and hospitalization from influenza (Neuzil et al., 2000). Children play an important role in the transmission of influenza within schools, families and communities. Vaccination with current influenza vaccines of approximately 80% of schoolchildren in a community has decreased respiratory illnesses in adults and excess deaths in the elderly (Reichert et al., 2001). This concept is known as community immunity or “herd immunity” and is thought to play an important part of protecting the community against disease. Because vaccinated people have antibodies that neutralize influenza virus, they are much less likely to transmit influenza virus to other people. Thus, even people who have not been vaccinated (and those whose vaccinations have become weakened or whose vaccines are not fully effective) often can be shielded by the herd immunity because vaccinated people around them are not getting sick. Herd immunity is more effective as the percentage of people vaccinated increases. It is thought that approximately 95% of the people in the community must be protected by a vaccine to achieve herd immunity. People who are not immunized increase the chance that they and others will get the disease.

Thus, the invention encompasses a method of inducing a substantially protective immunity to influenza virus infection to a population or a community in order to reduce the incidence of influenza virus infections among immunocompromised individuals or non-vaccinated individual buy administering VLPs of the invention to a population in a community. In one embodiment, most school-aged children are immunized against influenza virus by administering the VLPs of the invention. In another embodiment, most healthy individuals in a community to are immunized against influenza virus by administering the VLPs of the invention. In another embodiment VLPs of the invention are part of a “dynamic vaccination” strategy. Dynamic vaccination is the steady production of a low-efficacy vaccine that is related to an emerging pandemic strain, but due to an antigentic drift may not provide complete protection in a mammal (see Germann et al., 2006). Because of the uncertainty about the future identity of a pandemic strain, it is almost impossible to stockpile a well matched pandemic strain. However, vaccination with a poorly matched but potentially efficacious vaccine may slow the spread of the pandemic virus and/or reduce the severity of symptoms of a pandemic strain of influenza virus.

The invention also encompasses a vaccine comprising an influenza VLP, wherein said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof when administered to a subject. In another embodiment, said induction of substantial immunity reduces duration of influenza symptoms. In another embodiment, a said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises a VLP which comprises influenza HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, a said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises a VLP which consists essentially of influenza HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. Said VLPs may comprise additional influenza proteins and/or protein contaminates in negligible concentrations. In another embodiment, a said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises a VLP which consists of influenza HA, NA and M1 proteins. In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, a said vaccine induces substantial immunity to influenza virus infection or at least one symptom thereof in a subject, comprises a VLP comprises influenza proteins, wherein said influenza proteins consist of HA, NA and M1 proteins. These VLPs contain HA, NA and M1 and may contain additional cellular constituents such as cellular proteins, baculovirus proteins, lipids, carbohydrates etc., but do not contain additional influenza proteins (other than fragments of M1, HA and/or NA). In one embodiment, said influenza M1 protein comprises a K¹⁰¹ residue. In another embodiment, said influenza M1 protein is an avian influenza M1 protein. In another embodiment, said influenza HA, NA and M1 proteins are derived from an avian and/or seasonal influenza virus. In another embodiment, said HA and/or NA exhibits hemagglutinin activity and/or neuraminidase activity, respectfully. In another embodiment, said subject is a mammal. In another embodiment, said mammal is a human. In a further embodiment, said VLP is formulated with an adjuvant or immune stimulator. In another embodiment, where said vaccine is administered to a mammal. In a further embodiment, said mammal is a human.

This invention is further illustrated by the following examples which should not be construed as limiting. The contents of all references, patents and published patent applications cited throughout this application, as well as the Figures and the Sequence Listing, are incorporated herein by reference.

EXAMPLES Example 1 Materials and Methods

Avian influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 genes were expressed in Spodoptera frugiperda cells (Sf-95 cell line; ATCC PTA-4047) using the baculovirus bacmid expression system. The HA, NA, and M1 genes were synthesized by the reverse transcription and polymerase chain reaction (PCR) using RNA isolated from avian influenza A/Hong Kong/1073/99 (H9N2) virus (FIGS. 1, 2, and 3). For reverse transcription and PCR, oligonucleotide primers specific for avian influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 genes were used (Table 1). The cDNA copies of these genes were cloned initially into the bacterial subcloning vector, pCR2.1TOPO. From the resulting three pCR2.1TOPO-based plasmids, the HA, NA, and M1 genes were inserted downstream of the AcMNPV polyhedrin promoters in the baculovirus transfer vector, pFastBac1 (InVitrogen), resulting in three pFastBac1-based plasmids: pHA, pNA, and pM1 expressing these influenza virus genes, respectively. Then, a single pFastBac1-based plasmid pHAM was constructed encoding both the HA and M1 genes, each downstream from a separate polyhedrin promoter (FIG. 4). The nucleotide sequence of the NA gene with the adjacent 5′- and 3′-regions within the pNA plasmid was determined (SEQ ID NO:1) (FIG. 1). At the same time, the nucleotide sequences of the HA and M1 genes with the adjacent regions were also determined using the pHAM plasmid (SEQ ID NOs: 2 and 3) (FIGS. 2 and 3).

Finally, a restriction DNA fragment from the pHAM plasmid that encoded both the HA and M1 expression cassettes was cloned into the pNA plasmid. This resulted in the plasmid pNAHAM encoding avian influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 genes (FIG. 4).

Plasmid pNAHAM was used to construct a recombinant baculovirus containing influenza virus NA, HA, and M1 genes integrated into the genome, each downstream from a separate baculovirus polyhedrin promoter. Infection of permissive Sf-9S insect cells with the resulting recombinant baculovirus resulted in co-expression of these three influenza genes in each Sf-9S cell infected with such recombinant baculovirus.

The expression products in infected Sf-9S cells were characterized at 72 hr postinfection (p.i. by SDS-PAGE analysis, Coomassie blue protein staining, and Western immunoblot analysis using HA- and M1-specific antibodies (FIG. 5). Western immunoblot analysis was carried out using rabbit antibody raised against influenza virus type A/Hong Kong/1073/99 (H9N2) (CDC, Atlanta, Ga., USA), or mouse monoclonal antibody to influenza M1 protein (Serotec, UK). The HA, NA, and M1 proteins of the expected molecular weights (64 kd, 60 kd, and 31 kd, respectively) were detected by Western immunoblot analysis. Compared to the amount of HA protein detected in this assay, the NA protein showed lower reactivity with rabbit serum to influenza A/Hong Kong/1073/99 (H9N2) virus. Explanations for the amount of detectable NA protein included lower expression levels of the NA protein from Sf-9S cells infected with recombinant baculovirus as compared to the HA protein, lower reactivity of the NA with this serum under denaturing conditions in the Western immunoblot assay (due to the elimination of important NA epitopes during gel electrophoresis of membrane binding), lower NA-antibody avidity as compared to HA-antibody, or a lower abundance of NA-antibodies in the serum.

The culture medium from the Sf-9S cells infected with recombinant baculovirus expressing A/Hong Kong/1073/99 (H9N2) HA, NA, and M1 proteins was also probed for influenza proteins. The clarified culture supernatants were subjected to ultracentrifugation at 27,000 rpm in order to concentrate high-molecular protein complexes of influenza virus, such as subviral particles, VLP, complexes of VLP, and possibly, other self-assembled particulates comprised of influenza HA, NA, and M1 proteins. Pelleted protein products were resuspended in phosphate-buffered saline (PBS, pH 7.2) and further purified by ultracentrifugation on discontinuous 20-60% sucrose step gradients. Fractions from the sucrose gradients were collected and analyzed by SDS-PAGE analysis, Western immunoblot analysis, and electron microscopy.

Influenza HA and M1 proteins of the expected molecular weights were detected in multiple sucrose density gradient fractions by Coomassie blue staining and Western immunoblot analysis (FIG. 6, Table 1). This suggested that influenza viral proteins from infected Sf-9S cells are aggregated in complexes of high-molecular weight, such as capsomers, subviral particles, VLP, and/or VLP complexes. The NA proteins, although inconsistently detected by Coomassie blue staining and Western immunoblot analysis, which was likely due to the inability of the rabbit anti-influenza serum to recognize denatured NA protein in the Western immunoblot assay, were consistently detected in neuraminidase enzyme activity assay (FIG. 10).

TABLE 1 Fraction#* Titer  1 <1:5001  3 <1:500  5  1:500  7  1:1000  9  1:2000 11  1:2000 12  1:4000 14  1:500 16 <1:500 PBS** <1:500 A/Shangdong/9/93 <1:1000 *Fraction from 20-60% sucrose gradient **Negative Control ***Positive Control

SEQ ID Virus Strain Gene RT-PCR Primer NO Type A (H3N2) Hemagglutinin Forward 5′-A GGATCC ATG AAGACTATCATTGCTTTGAG-3′ 13 Sydney/5/97 (HA) Reverse 5′-A GGTACC TCAAATGCAAATGTTGCACCTAATG-3′ 14 Neuraminidase Forward 5′-GGGGACAAGTTTGTACAAAAAAGCAGGCTTAGAAG 15 (NA) GAGATAGAACC ATG AATCCAAATCAAAAGATAATAAC-3′ Reverse 5′-GGGGACCACTTTGTACAAGAAAGCTGGGTCCTATAT 16 AGGCATGAGATTGATGTCCGC-3′ Matrix (M1) Forward 5′-AAA GAATTC ATG AGTCTTCTAACCGAGGTCGAAACGTA-3′ 17 Reverse 5′-AAA TTCGAA TTACTCCAGCTCTATGCTGACAAAATGAC-3′ 18 M2 Forward 5′-A GAATC ATG AGTCTTCTAACCGAGGTCGAAACGCCT 19 ATCAGAAACGAATGGGGGTGC-3′ Reverse 5′-AAA TTCGAA TTACTCCAGCTCTATGCTGACAAAATGAC-3′ 20 Nucleoprotein Forward 5′-A GAATTC ATG GCGTCCCAAGGCACCAAACG-3′ 21 (NP) Reverse 5′-A 22 GCGGCCGCTTAATTGTCGTACTCCTCTGCATTGTCTCCGAA GAAATAAG-3′ Type B Harbin Hemagglutinin Forward 5′-A GAATTC ATG AAGGCAATAATTGTACTACTCATGG-3′ 23 (HA) Reverse 5′-A GCGGCCGCTTATAGACAGATGGAGCAAGAAACATTGTC 24 TCTGGAGA-3′ Neuraminidase Forward 5′-A GAATT C ATG CTACCTTCAACTATACAAACG-3′ 25 (NA) Reverse 5′-A 26 GCGGCCGCTTACAGAGCCATATCAACACCTGTGACAGTG-3′

The presence of high-molecular VLPs was confirmed by gel filtration chromatography. An aliquot from sucrose density gradient fractions containing influenza viral proteins was loaded onto a Sepharose CL-4B column for fractionation based on mass. The column was calibrated with dextran blue 2000, dextran yellow, and vitamin B12 (Amersham Pharmacia) with apparent molecular weights of 2,000,000; 20,000; and 1,357 daltons, respectively, and the void volume of the column was determined. As expected, high-molecular influenza viral proteins migrated in the void volume of the column, which was characteristic of macromolecular proteins, such as virus particles. Fractions were analyzed by Western immunoblot analysis to detect influenza and baculovirus proteins. For example, M1 proteins were detected in the void volume fractions, which also contained baculovirus proteins (FIG. 7).

The morphology of influenza VLPs and proteins in sucrose gradient fractions was elucidated by electron microscopy. For negative-staining electron microscopy, influenza proteins from two sucrose density gradient fractions were fixed with 2% glutaraldehyde in PBS, pH 7.2. Electron microscopic examination of negatively-stained samples revealed the presence of macromolecular protein complexes or VLPs in both fractions. These VLPs displayed different sizes including diameters of approximately 60 and 80 nm and morphologies (spheres). Larger complexes of both types of particles were also detected, as well as rod-shaped particles (FIG. 8). All observed macromolecular structures had spikes (peplomers) on their surfaces, which is characteristic of influenza viruses. Since the size and appearance of 80 nm particles was similar to particles of wild type influenza virus, these structures likely represented VLPs, which have distinct similarities to wild type influenza virions, including similar particle geometry, architecture, triangulation number, symmetry, and other characteristics. The smaller particles of approximately 60 nm may represent subviral particles that differ from VLPs both morphologically and structurally. Similar phenomenon of recombinant macromolecular proteins of different sizes and morphologies was also reported for other viruses. For example, recombinant core antigen (HBcAg) of hepatitis B virus forms particles of different sizes, which have different architecture and triangulation number T=4 and T=3, respectively (Crowther et al., 1994).

To characterize the functional properties of the purified influenza A/Hong Kong/1073/99 (H9N2) VLPs, samples were tested in a hemagglutination assay (FIG. 9) and a neuraminidase enzyme assay (FIG. 10). For the hemagglutination assay, 2-fold dilutions of purified influenza VLPs were mixed with 0.6% guinea pig red blood cells and incubated at 4° C. for 1 hr or 16 hr. The extent of hemagglutination was inspected visually and the highest dilution of recombinant influenza proteins capable of agglutinating red blood cells was determined and recorded (FIG. 9). Again, many fractions from the sucrose density gradient exhibited hemagglutination activity, suggesting that multiple macromolecular and monomeric forms of influenza proteins were present. The highest titer detected was 1:4000. In a control experiment, wild-type influenza A/Shangdong virus demonstrated a titer of 1:2000. The hemagglutination assay revealed that the recombinant VLPs consisting of influenza A/Hong Kong/1073/99 (H9N2) virus HA, NA, and M1 proteins were functionally active. This suggested that the assembly, conformation, and folding of the HA subunit proteins within the VLPs were similar or identical to that of the wild type influenza virus.

Additionally, a neuraminidase enzyme assay was performed on samples of purified H9N2 VLPs. The amount of neuraminidase activity in sucrose density gradient fractions was determined using fetuin as a substrate. In the neuraminidase assay, the neuraminidase cleaved sialic acid from substrate molecules to release sialic acid for measurement. Arsenite reagent was added to stop enzyme activity. The amount of sialic acid liberated was determined chemically with thiobarbituric acid that produces a pink color that was proportional to the amount of free sialic acid. The amount of color (chromophor) was measured spectrophotometrically at wavelength 549 nm. Using this method, neuraminidase activity was demonstrated in sucrose gradient fractions containing influenza VLPs (FIG. 10). As expected, the activity was observed in several fractions, with two peak fractions. As a positive control, wild type influenza virus was used. The wild type influenza virus exhibited neuraminidase enzyme activity comparable to that of purified influenza VLPs. These findings corroborated the HA results with regard to protein conformation and suggested that purified VLPs of influenza A/Hong Kong/1073/99 (H9N2) virus were functionally similar to wild type influenza virus.

The results from the above analyses and assays indicated that expression of influenza A/Hong Kong/1073/99 (H9N2) HA, NA, and M1 proteins was sufficient for the self-assembly and transport of functional VLPs from baculovirus-infected insect cells. Since these influenza VLPs represented self-assembled influenza structural proteins and demonstrated functional and biochemical properties similar to those of wild type influenza virus, these influenza VLPs conserved important structural conformations including surface epitopes necessary for effective influenza vaccines.

Example 2 RT-PCR Cloning of Avian Influenza A/Hong Kong/1073/99 Viral Genes

It is an object of the present invention to provide synthetic nucleic acid sequences capable of directing production of recombinant influenza virus proteins. Such synthetic nucleic acid sequences were obtained by reverse transcription and polymerase chain reaction (PCR) methods using influenza virus natural genomic RNA isolated from the virus. For the purpose of this application, nucleic acid sequence refers to RNA, DNA, cDNA or any synthetic variant thereof which encodes the protein.

Avian influenza A/Hong Kong/1073/99 (H9N2) virus was provided by Dr. K. Subbarao (Centers for Disease Control, Atlanta, Ga., USA). Viral genomic RNA was isolated by the acid phenol RNA extraction method under Biosafety Level 3 (BSL3) containment conditions at CDC using Trizol LS reagent (Invitrogen, Carlsbad, Calif. USA). cDNA molecules of the viral RNAs were obtained by reverse transcription using MuLV reverse transcriptase (InVitrogen) and PCR using oligonucleotide primers specific for HA, NA, and M1 proteins and Taq I DNA polymerase (InVitrogen) (Table 1). The PCR fragments were cloned into the bacterial subcloning vector, pCR2.1TOPO (InVitrogen), between Eco RI sites that resulted in three recombinant plasmids, containing the HA, NA, and M1 cDNA clones.

Example 3 RT-PCR Cloning of Human Influenza A/Sydney/5/94 (H3N2) Viral Genes

Influenza A/Sydney/5/97 (H3N2) Virus was obtained from Dr. M. Massare (Novavax, Inc., Rockville, Md.). Viral genomic RNA was isolated by the RNA acid phenol extraction method under BSL2 containment conditions at Novavax, Inc. using Trizol LS reagent (Invitrogen). cDNA molecules of the viral RNAs were obtained by reverse transcription and PCR using oligonucleotide primers specific for HA, NA, M1, M2, and NP proteins (Table 1). The PCR fragments were cloned into the bacterial subcloning vector, pCR2.1TOPO, between Eco RI sites that resulted in five recombinant plasmids, containing the HA, NA, M1, M2, and NP cDNA clones.

Example 4 Cloning of Avian Influenza A/Hong Kong/1073/99 Viral cDNAs into Baculovirus Transfer Vectors

From the pCR2.1TOPO-based plasmids, the HA, NA, or M1 genes were subcloned into pFastBac1 baculovirus transfer vector (InVitrogen) within the polyhedron locus and Tn7 att sites and downstream of the baculovirus polyhedrin promoter and upstream of the polyadenylation signal sequence. The viral genes were ligated with T4 DNA ligase. For the HA gene, a Bam HI-Kpn I DNA fragment from pCR2.1TOPO-HA was inserted into BamHI-KpnI digested pFastBac1 plasmid DNA. For the NA gene, an EcoRI DNA fragment from pCR2.1TOPO-NA was inserted into EcoRI digested pFastBac1 plasmid DNA. For the M1 gene, an Eco RI DNA fragment from pCR2.1TOPO-M1 was inserted into Eco RI digested pFastBac1 plasmid DNA. Competent E. coli DH5α bacteria (InVitrogen) were transformed with these DNA ligation reactions, transformed colonies resulted, and bacterial clones isolated. The resulting pFastBac1-based plasmids, pFastBac1-HA, pFastBac1-NA, and pFastBac1-M1 were characterized by restriction enzyme mapping on agarose gels (FIG. 4A). The nucleotide sequences as shown on FIGS. 1-3 of the cloned genes were determined by automated DNA sequencing. DNA sequence analysis showed that the cloned influenza HA, NA, and M1 genes were identical to the nucleotide sequences for these genes as published previously [NA, HA, and M1 genes of influenza A/Hong Kong/1073/99 (H9N2) (GenBank accession numbers AJ404629, AJ404626, and AJ278646, respectively)].

Example 5 Cloning of Human Influenza A/Sydney/5/97 Viral cDNAs into Baculovirus Transfer Vectors

From the pCR2.1TOPO-based plasmids, the HA, NA, M1, M2, and NP genes were subcloned into pFastBac1 baculovirus transfer vector within the polyhedron locus and Tn7 att sites and downstream of the baculovirus polyhedrin promoter and upstream of the polyadenylation signal sequence. The viral genes were ligated with T4 DNA ligase. For the HA gene, a Bam HI-Kpn I DNA fragment from pCR2.1TOPO-hHA3 was inserted into BamHI-KpnI digested pFastBac1 plasmid DNA. For the NA gene, an Eco RI DNA fragment from pCR2.1TOPO-hNA was inserted into EcoRI digested pFastBac1 plasmid DNA. For the M1 gene, an Eco RI DNA fragment from pCR2.1TOPO-hM1 was inserted into EcoRI digested pFastBac1 plasmid DNA. For the M2 gene, an EcoRI DNA fragment from pCR2.1TOPO-hM2 was inserted into EcoRI digested pFastBac1 plasmid DNA. For the NP gene, an EcoRI DNA fragment from pCR2.1TOPO-hNP was inserted into EcoRI digested pFastBac1 plasmid DNA. Competent E. coli DH5α bacteria were transformed with these DNA ligation reactions, transformed colonies resulted, and bacterial clones isolated. The resulting pFastBac 1-based plasmids, pFastBac1-hHA3, pFastBac1-hNA2, pFastBac1-hM1, pFASTBAC1-hM2, and pFASTBAC1-hNP were characterized by restriction enzyme mapping on agarose gels. The nucleotide sequences of the cloned genes were determined by automated DNA sequencing. DNA sequence analysis showed that the cloned influenza HA, NA, M1, M2, and NP genes were identical to the nucleotide sequences for these genes as published previously.

Example 6 Construction of Multigenic Baculovirus Transfer Vectors Encoding Multiple Avian Influenza A/Hong Kong/1073/99 Viral Genes

In order to construct pFastBac1-based bacmid transfer vectors expressing multiple influenza A/Hong Kong/1073/99 (H9N2) virus genes, initially a Sna BI-Hpa I DNA fragment from pFastBac1-M1 plasmid containing the M1 gene was cloned into Hpa I site of pFastBac1-HA. This resulted in pFastBac1-HAM plasmid encoding both HA and M1 genes within independent expression cassettes and expressed under the control of separate polyhedrin promoters.

Finally, a SnaBI-AvrII DNA fragment from pFastBac1-HAM containing the HA and M1 expression cassettes, was transferred into Hpa I-Avr II digested pFastBac1-NA plasmid DNA. This resulted in the plasmid pFastBac1-NAHAM encoding three independent expression cassettes for expression of influenza HA, NA, and M1 genes and expressed under the control of separate polyhedrin promoters (FIG. 4B).

In another example, the H3 gene from pFASTBAC1-hHA3 (see Example 5) was cloned into pFASTBAC1-NAHAM as a fourth influenza viral gene for the expression and production of heterotypic influenza VLPs.

Example 7 Generation of Multigenic Recombinant Baculovirus Encoding NA, HA, and M1 Genes of Avian Influenza A/Hong Kong/1073/99 Virus in Insect Cells

The resulting multigenic bacmid transfer vector pFastBac1-NAHAM was used to generate a multigenic recombinant baculovirus encoding avian influenza A/Hong Kong/1073/99 (H9N2) HA, NA, and M1 genes for expression in insect cells. Recombinant bacmid DNAs were produced by site-specific recombination at polyhedrin and Tn7 att DNA sequences between pFastBac1-NAHAM DNA and the AcMNPC baculovirus genome harbored in competent E. coli DH10BAC cells (InVitrogen) (FIG. 4B). Recombinant bacmid DNA was isolated by the mini-prep plasmid DNA method and transfected into Sf-9s cells using the cationic lipid CELLFECTIN (InVitrogen). Following transfection, recombinant baculoviruses were isolated, plaque purified, and amplified in Sf-9S insect cells. Virus stocks were prepared in Sf-9S insect cells and characterized for expression of avian influenza viral HA, NA, and M1 gene products. The resulting recombinant baculovirus was designated bNAHAM-H9N2.

Example 8 Expression of Recombinant Avian Influenza A/Hong Kong/1073/99 Proteins in Insect Cells

Sf-9S insect cells maintained as suspension cultures in shaker flasks at 28° C. in serum-free medium (HyQ SFM, HyClone, Ogden, Utah) were infected at a cell density of 2×10⁶ cells/ml with the recombinant baculovirus, bNAHAM-H9N2, at a multiplicity of infection (MOI) of 3 pfu/cell. The virus infection proceeded for 72 hrs. to allow expression of influenza proteins. Expression of avian influenza A/Hong Kong/1073/99 (H9N2) HA and M1 proteins in infected insect cells was confirmed by SDS-PAGE and Western immunoblot analyses. SDS-PAGE analysis was performed on 4-12% linear gradient NuPAGE gels (Invitrogen) under reduced and denaturing conditions. Primary antibodies in Western immunoblot analysis were polyclonal rabbit antiserum raised against avian influenza A/Hong Kong/1073/99 (H9N2) obtained from CDC and monoclonal murine antiserum to influenza M1 protein (Serotec, UK). Secondary antibodies for Western immunoblot analysis were alkaline phosphatase conjugated goat IgG antisera raised against rabbit or mouse IgG (H+L) (Kirkegaard and Perry Laboratories, Gaithersburg, Md., USA). Results of these analyses (FIG. 5) indicated that the HA and M1 proteins were expressed in the baculovirus-infected insect cells.

Example 9 Purification of Recombinant Avian Influenza H9N2 Virus-Like Particles and Macromolecular Protein Complexes

Culture supernatants (200 ml) from Sf-9S insect cells infected with the recombinant baculovirus bNAHAM-H9N2 that expressed avian influenza A/Hong Kong/1073/99 (H9N2) HA, NA, and M1 gene products were harvested by low speed centrifugation. Culture supernatants were clarified by centrifugation in a Sorval RC-5B superspeed centrifuge for 1 hr at 10,000×g and 4° C. using a GS-3 rotor. Virus and VLPs were isolated from clarified culture supernatants by centrifugation in a Sorval OTD-65 ultracentrifuge for 3 hr at 27,000 rpm and 4° C. using a Sorval TH-641 swinging bucket rotor. The virus pellet was resuspended in 1 ml of PBS (pH 7.2), loaded onto a 20-60% (w/v) discontinuous sucrose step gradient, and resolved by centrifugation in a Sorval OTD-65 ultracentrifuge for 16 hr at 27,000 rpm and 4° C. using a Sorval TH-641 rotor. Fractions (0.5 ml) were collected from the top of the sucrose gradient.

Influenza proteins in the sucrose gradient fractions were analyzed by SDS-PAGE and Western immunoblot analyses as described above in Example 6. The HA and M1 proteins were found in the same sucrose gradient fractions (FIG. 6) as shown by Western blot analysis and suggested that the HA and M1 proteins were associated as macromolecular protein complexes. Also the HA and M1 proteins were found in fractions throughout the sucrose gradient suggesting that these recombinant viral proteins were associated with macromolecular protein complexes of different densities and compositions.

Example 10 Analysis of Recombinant Avian Influenza H9N2 VLPs and Proteins by Gel Filtration Chromatography

Protein macromolecules such as VLPs and monomeric proteins migrate differently on gel filtration or size exclusion chromatographic columns based on their mass size and shape. To determine whether the recombinant influenza proteins from sucrose gradient fractions were monomeric proteins or macromolecular protein complexes such as VLPs, a chromatography column (7 mm×140 mm) with a resin bed volume of 14 ml of Sepharose CL-4B (Amersham) was prepared. The size exclusion column was equilibrated with PBS and calibrated with Dextran Blue 2000, Dextran Yellow, and Vitamin B12 (Amersham Pharmacia) with apparent molecular weights of 2,000,000; 20,000; and 1,357, respectively, to ascertain the column void volume. Dextran Blue 2000 eluted from the column in the void volume (6 ml fraction) also. As expected, the recombinant influenza protein complexes eluted from the column in the void volume (6 ml fraction). This result was characteristic of a high molecular weight macromolecular protein complex such as VLPs. Viral proteins in the column fractions were detected by Western immunoblot analysis as described above in Example 6. The M1 proteins were detected in the void volume fractions (FIG. 7). As expected baculovirus proteins were also in the void volume.

Example 11 Electron Microscopy of Recombinant Influenza VLPs

To determine whether the macromolecular protein complexes isolated on sucrose gradients and containing recombinant avian influenza proteins had morphologies similar to influenza virions, electron microscopic examination of negatively stained samples was performed. Recombinant avian influenza A/Hong Kong/1073/99 (H9N2) protein complexes were concentrated and purified from culture supernatants by ultracentrifugation on discontinuous sucrose gradients as described in Example 7. Aliquots of the sucrose gradient fractions were treated with a 2% glutaraldehyde in PBS, pH7.2, absorbed onto fresh discharged plastic/carbon-coated grids, and washed with distilled water. The samples were stained with 2% sodium phosphotungstate, pH 6.5, and observed using a transmission electron microscope (Philips). Electron micrographs of negatively-stained samples of recombinant avian influenza H9N2 protein complexes from two sucrose gradient fractions showed spherical and rod-shaped particles (FIG. 8) from two sucrose gradient fractions. The particles had different sizes (60 and 80 nm) and morphologies. Larger complexes of both types of particles were also detected, as well as rod-shaped particles (FIG. 8). All observed protein complex structures exhibited spike like surface projections resembling influenza virus HA and NA peplomers. Since the size and appearance of the 80 nm particles was similar to that of wild type influenza virus particles, these structures likely represented enveloped influenza VLPs. The smaller particles of approximately 60 nm probably represented subviral particles that differed from the above VLPs both morphologically and structurally.

Example 12 Analysis of Functional Characteristics of Influenza Proteins by Hemagglutination Assay

To determine whether the purified influenza VLPs and proteins possessed functional activities, such as hemagglutination and neuraminidase activity, which were characteristic for influenza virus, the purified influenza VLPs and proteins were tested in hemagglutination and neuraminidase assays.

For the hemagglutination assay, a series of 2-fold dilutions of sucrose gradient fractions containing influenza VLPs or positive control wild type influenza virus type A were prepared. Then they were mixed with 0.6% guinea pig red blood cells in PBS (pH 7.2) and incubated at 4° C. for 1 to 16 hr. As a negative control, PBS was used. The extent of hemagglutination was determined visually, and the highest dilution of fraction capable of agglutinating guinea pig red blood cells was determined (FIG. 9). The highest hemagglutination titer observed for the purified influenza VLPs and proteins was 1:4000, which was higher than the titer shown by the wild type influenza control, which was 1:2000.

Example 13 Analysis of Functional Characteristics of Influenza Proteins by Neuraminidase Assay

The amount of neuraminidase activity in influenza VLP-containing sucrose gradient fractions was determined by the neuraminidase assay. In this assay the NA (an enzyme) acted on the substrate (fetuin) and released sialic acid. Arsenite reagent was added to stop enzyme activity. The amount of sialic acid liberated was determined chemically with the thiobarbituric acid that produced a pink color in proportion to free sialic acid. The amount of color (chromophor) was measured in a spectrophotometer at wavelength 594 nm. The data, as depicted in FIG. 8, showed that a significant amount of sialic acid was produced by VLP-containing fractions of the sucrose gradients and that these fractions corresponded to those fractions exhibiting hemagglutination activity.

Example 14 Immunization of BALB/c Mice with Functional Homotypic Recombinant Influenza H9N2 VLPs

The immunogenicity of the recombinant influenza VLPs was ascertained by immunization of mice followed by Western blot analysis of immune sera. Recombinant VLPs (1 μg/injection) comprised of viral HA, NA, and M1 proteins from avian influenza virus type A/Honk Kong/1073/99 and purified on sucrose gradients were inoculated subcutaneously into the deltoid region of ten (10) female BALB/c mice at day 0 and day 28 (FIG. 11). PBS (pH 7.2) was administered similarly as a negative control into five (5) mice. The mice were bled from the supraorbital cavity at day−1 (pre-bleed), day 27 (primary bleed), and day 54 (secondary bleed). Sera were collected from blood samples following overnight clotting and centrifugation.

For Western blot analysis, 200 ng of inactivated avian influenza virus type A H9N2 or cold-adapted avian influenza virus type A H9N2, as well as See Blue Plus 2 pre-stained protein standards (InVitrogen), was denatured (95° C., 5 minutes) and subjected to electrophoresis under reduced conditions (10 mM β-mercaptoethanol) on 4-12% polyacrylamide gradient NuPAGE gels (InVitrogen) in MES buffer at 172 volts until the bromophenol blue tracking dye disappeared. For protein gels, the electrophoreses proteins were visualized by staining with Colloidal Coomassie Blue reagent (InVitrogen). Proteins were transferred from the gel to nitrocellulose membranes in methanol by the standard Western blot procedure. Sera from VLP-immunized mice and rabbits immunized with inactivated avian influenza virus H9N2 (positive control sera) were diluted 1:25 and 1:100, respectively, in PBS solution (pH 7.2) and used as primary antibody. Protein bound membranes, which were blocked with 5% casein, were reacted with primary antisera for 60 minutes at room temperature with constant shaking. Following washing of primary antibody membranes with phosphate buffered saline solution containing Tween 20, secondary antisera [goat anti-murine IgG—alkaline phosphatase conjugate (1:10,000) or goat anti-rabbit IgG—alkaline phosphatase conjugate (1:10,000)] were reacted 60 minutes with the membrane. Following washing of secondary antibody membranes with phosphate buffered saline solution containing Tween 20, antibody-binding proteins on the membranes were visualized by development with the chromogenic substrate such as NBT/BCIP (InVitrogen).

The results of Western blot analysis (FIG. 12) were that proteins with molecular weights similar to viral HA and M1 proteins (75 and 30 kd, respectively) bound to positive control sera (FIG. 12B) and sera from mice immunized with the recombinant influenza H9N2 VLPs (FIG. 12A). These results indicated that the recombinant influenza H9N2 VLPs alone were immunogenic in mice by this route of administration.

Example 15 Kong/1073/99 (H9N2) VLP Immunogenicity and Challenge Study in BALB/c Mice

BALB/C mice were immunized with H9N2 VLPs (1 μg HA or 10 μg HA/dose), with or without 100 μg Novasome adjuvant, on day 0 and day 21 and challenged with homologous infectious virus IN on day 57. Mice were bled on days 0, 27 and 57 with the serum assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) using turkey RBCs, and influenza by ELISA. Results of this study are shown in FIG. 13 through FIG. 16.

High titers of H9N2 antibodies were induced after a single immunization (primary) with H9N2 VLP vaccine without or with Novasomes and a dose of 10 μg VLPs containing 1 μg HA (FIG. 13). Specific antibody titers were increased about half to one log following a booster immunization.

After immunization and a boost with 1 μg of HA in the form of H9N2 VLPs the serum HI levels were at or above the level generally considered protective (log 2=5) in all animals (FIG. 14, lower left panel). H9N2 VLPs formulated with Novasome adjuvant increased HI responses about 2 fold following primary immunization and about 4 fold after the booster (FIG. 14, lower right panel). Purified subunit H9N2 hemagglutinin also induced protective levels of HI antibodies after boosting and Novasomes again increased HI antibody responses by about 2 fold after the primary and 4 fold after the booster immunizations (FIG. 14, upper panels). The level of HI antibody induced with 10 μg of HA given as a subunit vaccine was equivalent to 1 μg of HA presented in the form of a VLP.

In addition, weight loss was significantly less in the mice immunized with H9N2 VLPs or with VLPs plus adjuvant compared to unvaccinated control animals (FIG. 15). There was no statistical difference in weight loss in the groups immunized with H9N2 VLPs and H9N2 VLPs plus Novasome adjuvant.

Likewise, lung virus titers at 3 and 5 days post challenge with H9N2 virus were significantly reduced in mice immunized with H9N2 VLPs (FIG. 16). At day 3 when the influenza virus titers peak in the lung tissues, mice immunized with H9N2 VLPs plus Novasomes® had a significantly greater reduction in virus titer compared to mice immunized with VLPs alone and the unvaccinated control mice.

Example 16 A/Fujian/411/2002 (H3N2) VLP Immunogenicity and Cross Reactivity Between Several Influenza Strains

BALB/c mice were immunized with A/Fujian/411/2002 VLPs (3.0, 0.6, 0.12 and 0.24 μg HA/dose), twice IM and N. Mice were bled on days 0 and 35. The serum was then assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) using turkey RBCs, and for anti-influenza antibodies by ELISA. Results of this study are shown on FIGS. 17A, 17B and 17C. These results indicate that an immune response was mounted both IM and IN against HA and NA.

Example 17 Determination of the IgG Isotypes in Mouse after Inoculation with H3N2 VLPs

Mice were inoculated with VLPs intramuscularly and intranasal. At week 5 sera was collected and assayed to distinguish between IgG isotypes.

Sera was tested on plates coated with purified HA (Protein Sciences) A/Wyoming/3/2003 using an ELISA assay. Serial five-fold dilutions of sera was added to the wells and the plates were incubated. Next, the biotinylated goat anti-mouse Ig, or anti-mouse IgG1, anti-mouse IgG2a, anti-mouse IgG2b and anti-mouse IgG3. Then, streptavidine-peroxidase was added to the wells. Bound conjugates were detected. Results are illustrated on FIGS. 18A and B. These results illustrate that IgG2a are the most abundant isotype in an immune response against VLPs in mouse.

Example 18 A/Hong Kong/1073/99 (H9N2) VLP Dose-Ranging Study in SD Rats

SD rats (n=6 per dose) were immunized on day 0 and day 21 with purified A/Hong Kong/1073/99 (H9N2) VLPs diluted with PBS at neutral pH to 0.12, 0.6, 3.0, and 15.0 μg HA or with PBS alone. Blood samples were taken from the animals on day 0, day 21, day 35 and day 49 and the serum assayed for hemagglutination inhibition assay (HI) to detect functional antibodies able to inhibit the binding function of the HA. The dosage was based on HA content as measured using SDS-PAGE and scanning densitometry of purified H9N2 VLPs. Hemagglutinin inhibition assay titer results are depicted in FIG. 19. A single 0.6 μg HA dose of H9N2 VLPs or two doses of 0.12 μg HA produced protective levels of HI antibodies in rats. These data indicate that a lower amount of HA can induce a protective response when said HA is part of a VLP.

Example 19 Kong/1073/99 (H9N2) VLP Immunogenicity

BALB/C mice were immunized with H9N2 VLPs (0.12, 0.6 μg HA/dose), with or without 100 μg Novasome and Alum adjuvant, on day 0 and day 21 and challenged with homologous infectious virus IN on day 57. Mice were also immunized with 3.0 and 15.0 μg HA/dose (no adjuvant). Mice were bled on days 0, 21, 35 and 49 with the serum assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) using turkey RBCs, and influenza by ELISA. Results of this study are shown in FIGS. 20 A and B.

The results indicate that a more robust overall immune response was observed when the VLPs were administered with an adjuvant. However, a protective response was elicited with 0.12 μg HA/dose at week 3 when compared to the VLPs formulation with Alum and VLPs with no adjuvant. Also in week 7, the VLPs comprising Novasomes had about 2 log increase in HI titer as compared to the VLP with Alum. The robustness of the response was similar to VLPs administered at 3.0 and 15.0 μg HA/dose without an adjuvant. These results indicate that Novasomes elicit a more robust response as compared to Alum. In addition, a protective immune response can be achieved with 25× less VLPs when said VLPs are administered in a formulation comprising Novasomes.

Also, in the 0.6 μg HA/dose data, the Novasome formulation had an about 1.5 log greater response than compared to Alum. The immune responses were similar in magnitude to VLPs administered in 3.0 and 15.0 μg HA/dose without adjuvant. These results indicate that with an adjuvant, approximately 5× less VLPs are needed to be administered to achieve a protective response.

Also, FIG. 20B depicts the HI titer of H9N2 VLPs using different formulations of Novasomes. The following are the formulas used in the experiment:

Group 1: H9N2 VLP (0.1 μg) (n=5) Group 2: H9N2 VLP (0.1 μg) w/ DCW neat) (n=5) Group 3: H9N2 VLP (0.1 μg) w/ DCW 1:3) (n=5) Group 4: H9N2 VLP (0.1 μg) w/ DCW 1:9) (n=5) Group 5: H9N2 VLP (0.1 μg) w/ DCW 1:27) (n=5) Group 6: H9N2 VLP (0.1 μg) w/ NVAX 1) (n=5) Group 7: H9N2 VLP (0.1 μg) w/ NVAX 2) (n=5) Group 8: H9N2 VLP (0.1 μg) w/ NVAX 3) (n=5) Group 9: H9N2 VLP (0.1 μg) w/ NVAX 4) (n=5) Group 10: H9N2 VLP (0.1 μg) w/ NVAX 5) (n=5) Group 11: H9N2 VLP (0.1 μg) w/ Alum-OH) (n=5) Group 12: H9N2 VLP (0.1 μg) w/ CpG) (n=5) Group 13: PBS (0.6 μg) (n=5) Group 14: H3 VLPs (0.6 μg) (n=5) Group 15: H5 VLPs (0.6 μg) (n=8)

-   -   H9: (Lot#11005)     -   DCW: Novasomes (Lot#121505-2, Polyoxyethylene-2-cetyl ether,         Cholesterol, Superfined soybean oil, and Cetylpridinium         chloride)     -   NVAX 1: B35P83, MF-59 replica (Squalene, Polysorbate, and Span)     -   NVAX 2: B35P87 (Soybean Oil, Brij, Cholesterol, Pluronic F-68)     -   NVAX 3: B35P88 (Soybean Oil, Brij, Cholesterol, Pluronic F-68,         and Polyethyleneimine)     -   NVAX 4: B31P60 (Squalene, Brij, Cholesterol, Oleic acid)     -   NVAX 5: B31P63 (Soybean oil, Glyceryl monostearate, Cholesterol,         Polysorbate)     -   CpG: (Lot#1026004)     -   H5: (Lot#22406)

FIG. 21 depicts and H9N2 VLP dose response curve. This data indicates that a dose of VLPs at 0.6 μg HA/dose is the minimum to elicit a protective immune response in mice after 3 weeks.

Example 20 Materials and Methods for Ferret Studies

Ferrets were purchased from Triple F Farms (FFF, Sayre, Pa.). All ferrets purchased has an HAI titer of less that 10 hemagglutination units. Approximately two days prior to vaccination, animals were implanted with a temperature transponder (BioMedic Data Systems, Inc.). Animal (6 animals/group) were vaccinated on day 0 either with (1) PBS (negative control, group one), (2) H3N2 influenza VLPs @ 15 μg of H3 (group 2), (3) H3N2 influenza VLPs @ 3 μg of H3 (group 2), (4) H3N2 influenza VLPs @ 0.6 μg of H3 (group 3), (5) H3N2 influenza VLPs @ 0.12 μg of H3 (group 5), or (6) rH3HA @ 15 μg (group 6). On day 21 animals were boosted with vaccine Animals were bled on days 0 (prior to vaccination), day 21 (prior to vaccine boost), and day 42 Animals were assessed for clinical signs of adverse vaccine effects once weekly throughout the study period. Similar studies were performed with other influenza VLPs.

HAI Levels in Ferret Sera

Ferret sera were obtained from FFF, treated with Receptor Destroying Enzyme (RDE) and tested in a hemagglutination inhibition (HAI) assay by standard procedures (Kendal et al. (1982)). All ferrets that were chosen for the study tested negative (HAI≦10) for pre-existing antibodies to currently circulating human influenza virus (A/New Calcdonia/20/99 (H1N1), A panama/2007/99 (H3N2), A/Wellington/01/04 (H2N3) and B/Sichuan/379/99 and H5N1).

Ferrets

Approximately 8 month-old, influenza naïve, castrated and descented, male Fitch ferrets (Mustela putorius furo) were purchased form FFF. Animals were housed in stainless steel rabbit cages (Shor-line, KS) containing Sani-chips Laboratory Animal Bedding (P.J. Murphy Forest Products, NJ). Ferrets were provided with Teklad Global Ferret Diet (Harlan Teklad, Wis.) and fresh water ad libitum. Pans were changed three times each week, and cages were cleaned biweekly.

Vaccinations and Blood Collection of Ferrets

The vaccine, H3N2 influenza VLPs or H9N2 influenza VLPs and controls, for example, rH3NA (A/Wyoming/3/2003) and PBS (negative control) were stored at 4° C. prior to use. For most studies, six groups of ferrets (N-6/group) were vaccinated intramuscularly with either concentration of vaccine or control in a volume of 0.5 ml.

Prior to blood collection and vaccination, animals were anesthetized by intramuscular injection into the inner thigh with a solution of Katamine (25 mg/kg, Atropine (0.05 mg/kg) and Xylazine (2.0 mg/kg) “KAX.” Once under anesthesia, ferrets were positioned in dorsal recumbency and blood was collected (volume between 0.5 and 1.0 ml) from the anterior vena cava using a 23 gauge 1″ needle connected to a 1 cc tuberculin syringe. Blood was transferred to a tube containing a serum separator and clot activator and allowed to clot at room temperature. Tubes were centrifuged and sera was removed and frozen at −80° C. Blood was collected prior to vaccination (day 0), prior to boost (day 21) and day 42 and tested by HAI assay.

Monitoring of Ferrets

Temperatures were measured weekly at approximately the same time throughout the study period. Pre-vaccination values were averaged to obtain a baseline temperature for each ferret. The change in temperature (in degrees Fahrenheit) was calculated at each time point for each animal. Ferrets were examined weekly for clinical signs of adverse vaccine effects, including temperature, weight loss, loss of activity, nasal discharge, sneezing and diarrhea. A scoring system bases on that described by Reuman et al. (1989) was used to assess activity level where 0=alert and playful; 1=alert but playful only when stimulated; 2=alert by not playful when stimulated; 3=neither alert not playful when stimulated. Based on the scores for each animal in a group, a relative inactivity index was calculated as Σ(day0−Day 42)[activity score+1]/Σ(day0−Day 42), where n equals the total number of observations. A value of 1 was added to each base score so that a score of “0” could be divided by a denominator, resulting in an index value of 1.0.

Serum Preparations

Sera generally have low levels of non-specific inhibitors on hemagglutination. To inactivate these non-specific inhibitors, sera were treated with (RDE) prior to being tested. Briefly, three part RDE was added to one part sera and incubated overnight at 37° C. RDE was inactivated by incubation at 56° C. for approximately 30 minutes. Following inactivation of RDE, PBS was added to the sample for a final serum dilution of 1:10 (RDE-Tx). The diluted RDE-Tx sera was stored at 4° C. prior to testing (for 7 days) or stored at −20° C.

Preparation Turkey Erythrocytes:

Human influenza viruses bind to sialic acid receptors containing N-acetylneuraminic acid α2,6-galactose linkages. Avian influenza viruses bind to sialic acid receptors containing N-acetylneuraminic acid α2,3 galactose (α2,3 linkages) and express both α2,3 and α2,6 linkages. Turkey erythocytes (TRBC) are used for the HAI assay since A/Fujian is a human influenza virus. The TRBCs adjusted with PBS to achieve a 0.5% vol/vol suspension. The cells are kept at 4° C. and used within 72 hours of preparation.

HAI Assay

The HAI assay was adapted from the CDC laboratory-based influenza surveillance manual (Kendal et al. (1982) Concepts and procedures for laboratory based influenza surveillance, U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, Atlanta, Ga., herein incorporated by reference in its entirety for all purposes). RDE-Tx sera was serially two-fold diluted in v-bottom microtiter plates. An equal volume of virus adjusted, adjusted to approximately 8 HAU/50ul was added to each well. The plates were covered and incubated at room temperature for 15 minutes followed by the addition of 0.5% TRBC. The plates were mixed by agitation, covered, and the TRBC were allowed to settle for 30 minutes at room temperature. The HAI titer was determined by the reciprocal dilution of the last row which contained non-agglutinated TRBC. Positive and negative serum controls were included for each plate.

Example 21 A/Hong Kong/1073/99 (H9N2) VLP Dose-Ranging Study in Ferrets

Ferrets, serologically negative by hemagglutination inhibition for influenza viruses, were used to assess the antibody and HI titer after an inoculation with H9N2 VLPs. Ferrets were bled on days 0, and 21 days with the serum assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) using turkey RBCs, and for anti-influenza antibodies by ELISA. Results are illustrated in FIG. 22. These results show HI titers corresponding to protective antibody levels at VLP doses of 1.5 and 15 μg.

Example 21 Vaccination of H3N2 VLPs in Ferrets

Ferrets were vaccinated at day 0, and given a boost on day 21 with different strains of H3N2 VLPs at different dosages (HA dosages of 0.12, 0.6, 3.0, 15.0 μg). The positive control was rH3HA at 15 μg and PBS alone is the negative control. Sera, as described above, were taken from the ferrets on day 0 prior to vaccination, day 21 (prior to boost) and day 42. An HI assay was conducted on the serum samples to determine if there was an immune response against the VLPs. These data are illustration on FIG. 23. These data indicate that H3N2 VLPs, when introduced into ferrets, do induce an immune response. Thus, the H3N2 VLPs are immunogenic in ferrets.

Example 22 RT-PCR and Cloning of HA, NA, and M1 Genes of Influenza A/Indonesia/5/05 (H5N1) Virus

Clade 2 influenza virus, strain A/Indonesia/5/05 (H5N1) viral RNA was extracted using Trizol LS (Invitrogen, Carlsbad, Calif.) under BSL-3 containment conditions. Reverse transcription (RT) and PCR were performed on extracted viral RNA using the One-Step RT-PCR system (Invitrogen) with gene-specific oligonucleotide primers. The following primer pairs were used for the synthesis of the H5N1 hemagglutinin (HA), neuraminidase (NA), and matrix (M1) genes, respectively:

(SEQ ID NO: 4) 5′-AACGGTCCGATGGAGAAAATAGTGCTTCTTC-3′ and (HA) (SEQ ID NO: 5) 5′-AAAGCTTTTAAATGCAAATTCTGCATTGTAACG-3′; (SEQ ID NO: 6) 5′-AACGGTCCGATGAATCCAAATCAGAAGATAAT-3′ and (NA) (SEQ ID NO: 7) 5′-AAAGCTTCTACTTGTCAATGGTGAATGGCAAC-3′;   and (SEQ ID NO: 8) 5′-AACGGTCCGATGAGTCTTCTAACCGAGGTC-3′ and (M1) (SEQ ID NO: 9) 5′-AAAGCTTTCACTTGAATCGCTGCATCTGCAC-3′. (ATG codons are underlined)

Following RT-PCR, cDNA fragments containing influenza HA, NA, and M1 genes with molecular weights of 1.7, 1.4, and 0.7 kB, respectively, were cloned into the pCR2.1-TOPO vector (Invitrogen). The nucleotide sequences of the HA, NA, and M1 genes were determined by DNA sequencing. A similar strategy was followed for cloning a clade 1 H5N1 influenza virus from Vietnam/1203/2003.

Example 23 Generation of Recombinant Baculoviruses Comprising H5N1

The HA gene was cloned as a RsrII-HindIII DNA fragment (1.7 kb) downstream of the AcMNPV polyhedrin promoter within pFastBac1 bacmid transfer vector (Invitrogen) digested with RsrII and HindIII. Similarly, the NA and M1 genes were cloned as EcoRI-HindIII DNA fragments (1.4 and 0.8 kb, respectively) into EcoRI-HindIII-digested pFastBac1 plasmid DNA. The three resulting baculovirus transfer plasmids pHA, pNA, and pM1 containing influenza A/Indonesia/5/05 (H5N1) virus HA, NA, and M1 genes, respectively, were used to generate recombinant bacmids.

Bacmids were produced by site-specific homologous recombination following transformation of bacmid transfer plasmids containing influenza genes into E. coli DH10Bac competent cells, which contained the AcMNPV baculovirus genome (Invitrogen). The recombinant bacmid DNA was transfected into the Sf9 insect cells.

Nucleotide sequences of the Indonesia/5/05 HA, NA, and M1 genes. HA (SEQ ID NO: 10) ATGGAGAAAATAGTGCTTCTTCTTGCAATAGTCAGTCTTGTTAAAAGTGATCAGATTTGC ATTGGTTACCATGCAAACAATTCAACAGAGCAGGTTGACACAATCATGGAAAAGAACGTT ACTGTTACACATGCCCAAGACATACTGGAAAAGACACACAACGGGAAGCTCTGCGATCTA GATGGAGTGAAGCCTCTAATTTTAAGAGATTGTAGTGTAGCTGGATGGCTCCTCGGGAAC CCAATGTGTGACGAATTCATCAATGTACCGGAATGGTCTTACATAGTGGAGAAGGCCAAT CCAACCAATGACCTCTGTTACCCAGGGAGTTTCAACGACTATGAAGAACTGAAACACCTA TTGAGCAGAATAAACCATTTTGAGAAAATTCAAATCATCCCCAAAAGTTCTTGGTCCGAT CATGAAGCCTCATCAGGAGTGAGCTCAGCATGTCCATACCTGGGAAGTCCCTCCTTTTTT AGAAATGTGGTATGGCTTATCAAAAAGAACAGTACATACCCAACAATAAAGAAAAGCTAC AATAATACCAACCAAGAAGATCTTTTGGTACTGTGGGGAATTCACCATCCTAATGATGCG GCAGAGCAGACAAGGCTATATCAAAACCCAACCACCTATATTTCCATTGGGACATCAACA CTAAACCAGAGATTGGTACCAAAAATAGCTACTAGATCCAAAGTAAACGGGCAAAGTGGA AGGATGGAGTTCTTCTGGACAATTTTAAAACCTAATGATGCAATCAACTTCGAGAGTAAT GGAAATTTCATTGCTCCAGAATATGCATACAAAATTGTCAAGAAAGGGGACTCAGCAATT ATGAAAAGTGAATTGGAATATGGTAACTGCAACACCAAGTGTCAAACTCCAATGGGGGCG ATAAACTCTAGTATGCCATTCCACAACATACACCCTCTCACCATCGGGGAATGCCCCAAA TATGTGAAATCAAACAGATTAGTCCTTGCAACAGGGCTCAGAAATAGCCCTCAAAGAGAG AGCAGAAGAAAAAAGAGAGGACTATTTGGAGCTATAGCAGGTTTTATAGAGGGAGGATGG CAGGGAATGGTAGATGGTTGGTATGGGTACCACCATAGCAATGAGCAGGGGAGTGGGTAC GCTGCAGACAAAGAATCCACTCAAAAGGCAATAGATGGAGTCACCAATAAGGTCAACTCA ATCATTGACAAAATGAACACTCAGTTTGAGGCCGTTGGAAGGGAATTTAATAACTTAGAA AGGAGAATAGAGAATTTAAACAAGAAGATGGAAGACGGGTTTCTAGATGTCTGGACTTAT AATGCCGAACTTCTGGTTCTCATGGAAAATGAGAGAACTCTAGACTTTCATGACTCAAAT GTTAAGAACCTCTACGACAAGGTCCGACTACAGCTTAGGGATAATGCAAAGGAGCTGGGT AACGGTTGTTTCGAGTTCTATCACAAATGTGATAATGAATGTATGGAAAGTATAAGAAAC GGAACGTACAACTATCCGCAGTATTCAGAAGAAGCAAGATTAAAAAGAGAGGAAATAAGT GGGGTAAAATTGGAATCAATAGGAACTTACCAAATACTGTCAATTTATTCAACAGTGGCG AGTTCCCTAGCACTGGCAATCATGATGGCTGGTCTATCTTTATGGATGTGCTCCAATGGA TCGTTACAATGCAGAATTTGCATTTAA NA (SEQ ID NO: 11) ATGAATCCAAATCAGAAGATAATAACCATTGGATCAATCTGTATGGTAATTGGAATAGTT AGCTTAATGTTACAAATTGGGAACATGATCTCAATATGGGTCAGTCATTCAATTCAGACA GGGAATCAACACCAAGCTGAATCAATCAGCAATACTAACCCTCTTACTGAGAAAGCTGTG GCTTCAGTAACATTAGCGGGCAATTCATCTCTTTGCCCCATTAGAGGATGGGCTGTACAC AGTAAGGACAACAATATAAGGATCGGTTCCAAGGGGGATGTGTTTGTTATTAGAGAGCCG TTCATCTCATGCTCCCACCTGGAATGCAGAACTTTCTTCTTGACTCAGGGAGCCTTGCTG AATGACAAGCACTCCAACGGGACTGTCAAAGACAGAAGCCCTCACAGAACATTAATGAGT TGTCCTGTGGGTGAGGCTCCCTCTCCATATAACTCAAGGTTTGAGTCTGTTGCTTGGTCA GCAAGTGCTTGCCATGATGGCACCAGTTGGTTGACAATTGGAATTTCTGGCCCAGACAAT GAGGCTGTGGCTGTATTGAAATACAATGGCATAATAACAGACACTATCAAGAGTTGGAGG AACAACATACTGAGAACTCAAGAGTCTGAATGTGCATGTGTAAATGGCTCTTGCTTTACT GTAATGACTGATGGACCAAGTGATGGGCAGGCATCATATAAGATCTTCAAAATGGAAAAA GGAAAAGTGGTCAAATCAGTCGAATTGGATGCTCCTAATTATCACTATGAGGAATGCTCC TGTTATCCTGATGCCGGCGAAATCACATGTGTTTGCAGGGATAATTGGCATGGCTCAAAT AGGCCATGGGTATCTTTCAATCAAAATTTGGAGTATCAAATAGGATATATATGCAGTGGA GTTTTCGGAGACAATCCACGCCCCAATGATGGAACAGGTAGTTGTGGCCCGATGTCCCCT AACGGGGCATATGGGGTAAAAGGGTTTTCATTTAAATACGGCAATGGTGTTTGGATCGGG AGAACCAAAAGCACTAATTCCAGGAGCGGCTTTGAAATGATTTGGGATCCAAATGGGTGG ACTGGAACGGACAGTAGCTTTTCAGTGAAACAAGATATAGTAGCAATAACTGATTGGTCA GGATATAGCGGGAGTTTTGTCCAGCATCCAGAACTGACAGGATTAGATTGCATAAGACCT TGTTTCTGGGTTGAGTTAATCAGAGGGCGGCCCAAAGAGAGCACAATTTGGACTAGTGGG AGCAGCATATCTTTTTGTGGTGTAAATAGTGACACTGTGAGTTGGTCTTGGCCAGACGGT GCTGAGTTGCCATTCACCATTGACAAGTAG M1 (SEQ ID NO: 12) ATGAGTCTTCTAACCGAGGTCGAAACGTACGTTCTCTCTATCATCCCGTCAGGCCCCCTC AAAGCCGAGATCGCGCAGAAACTTGAAGATGTCTTTGCAGGAAAGAACACCGATCTCGAG GCTCTCATGGAGTGGCTGAAGACAAGACCAATCCTGTCACCTCTGACTAAAGGGATTTTG GGATTTGTATTCACGCTCACCGTGCCCAGTGAGCGAGGACTGCAGCGTAGACGCTTTGTC CAGAATGCCCTAAATGGAAATGGAGATCCAAATAATATGGATAGGGCAGTTAAGCTATAT AAGAAGCTGAAAAGAGAAATAACATTCCATGGGGCTAAAGAGGTTTCACTCAGCTACTCA ACCGGTGCACTTGCCAGTTGCATGGGTCTCATATACAACAGGATGGGAACGGTGACTACG GAAGTGGCTTTTGGCCTAGTGTGTGCCACTTGTGAGCAGATTGCAGATTCACAGCATCGG TCTCACAGGCAGATGGCAACTATCACCAACCCACTAATCAGGCATGAAAACAGAATGGTG CTGGCCAGCACTACAGCTAAGGCTATGGAGCAGATGGCGGGATCAAGTGAGCAGGCAGCG GAAGCCATGGAGGTCGCTAATCAGGCTAGGCAGATGGTGCAGGCAATGAGGACAATTGGA ACTCATCCTAACTCTAGTGCTGGTCTGAGAGATAATCTTCTTGAAAATTTGCAGGCCTAC CAGAAACGAATGGGAGTGCAGATGCAGCGATTCAAGTGA

One cloned HA gene, pHA5, contained two nucleotide changes, nt #1172 and nt #1508 (in the wt), as compared to the wild-type HA gene sequence. A similar strategy was followed for constructing and creating clade 1 H5N1 influenza virus from Vietnam/1203/2003 VLPs (see below). The alignments of pHA5 nucleotide and amino acid sequences follow.

Example 26 Generation of Influenza A/Indonesia/5/05 HA, NA, and M1 Genes Optimized for Efficient Expression in Sf9 Cells

The following polypeptides were derived from codon-optimized nucleotides corresponding to the Indonesia/5/05 HA gene (see example 31). The codon-optimized nucleotides were designed and produced (Geneart GMBH, Regensburg, FRG) according to the methods disclosed in US patent publication 2005/0118191, herein incorporated by reference in its entirety for all proposes. See Example 31 for nucleic acid sequences

Vac2-hac-opt (unmodified aa sequence) (SEQ ID NO: 27) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE SRRKKRGLFG AIAGFIEGGW QGMVDGWYGY HHSNEQGSGY AADKESTQKA IDGVTNKVNS IIDKMNTQFE AVGREFNNLE RRIENLNKKM EDGFLDVWTY NAELLVLMEN ERTLDFHDSN VKNLYDKVRL QLRDNAKELG NGCFEFYHKC DNECMESIRN GTYNYPQYSE EARLKREEIS GVKLESIGTY QILSIYSTVA SSLALAIMMA GLSLWMCSNG SLQCRICI* Vac2-hac-spc-opt (modified, signal peptide from Chitinase, underlined) (SEQ ID NO: 28) Mplykllnvlwlvavsnaip DQICIGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE SRRKKRGLFG AIAGFIEGGW QGMVDGWYGY HHSNEQGSGY AADKESTQKA IDGVTNKVNS IIDKMNTQFE AVGREFNNLE RRIENLNKKM EDGFLDVWTY NAELLVLMEN ERTLDFHDSN VKNLYDKVRL QLRDNAKELG NGCFEFYHKC DNECMESIRN GTYNYPQYSE EARLKREEIS GVKLESIGTY QILSIYSTVA SSLALAIMMA GLSLWMCSNG SLQCRICI* Vac2-hac-sph9-opt (modified, signal peptide from H9, underlined) (SEQ ID NO: 29) METISLITIL LVVTASNA DQICIGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE SRRKKRGLFG AIAGFIEGGW QGMVDGWYGY HHSNEQGSGY AADKESTQKA IDGVTNKVNS IIDKMNTQFE AVGREFNNLE RRIENLNKKM EDGFLDVWTY NAELLVLMEN ERTLDFHDSN VKNLYDKVRL QLRDNAKELG NGCFEFYHKC DNECMESIRN GTYNYPQYSE EARLKREEIS GVKLESIGTY QILSIYSTVA SSLALAIMMA GLSLWMCSNG SLQCRICI* Vac2-hac-cs-opt (-is the modified cleavage site) (SEQ ID NO: 30) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE S----RGLFG AIAGFIEGGW QGMVDGWYGY HHSNEQGSGY AADKESTQKA IDGVTNKVNS IIDKMNTQFE AVGREFNNLE RRIENLNKKM EDGFLDVWTY NAELLVLMEN ERTLDFHDSN VKNLYDKVRL QLRDNAKELG NGCFEFYHKC DNECMESIRN GTYNYPQYSE EARLKREEIS GVKLESIGTY QILSIYSTVA SSLALAIMMA GLSLWMCSNG SLQCRICI*

The following polypeptides corresponding to unmodified, codon-optimized NA and M1 genes where also synthesized.

Vac2-naj-opt (neuraminidase) (SEQ ID NO: 31) MNPNQKIITI GSICMVIGIV SLMLQIGNMI SIWVSHSIQT GNQHQAESIS NTNPLTEKAV ASVTLAGNSS LCPIRGWAVH SKDNNIRIGS KGDVFVIREP FISCSHLECR TFFLTQGALL NDKHSNGTVK DRSPHRTLMS CPVGEAPSPY NSRFESVAWS ASACHDGTSW LTIGISGPDN EAVAVLKYNG IITDTIKSWR NNILRTQESE CACVNGSCFT VMTDGPSDGQ ASYKIFKMEK GKVVKSVELD APNYHYEECS CYPDAGEITC VCRDNWHGSN RPWVSFNQNL EYQIGYICSG VFGDNPRPND GTGSCGPMSP NGAYGVKGFS FKYGNGVWIG RTKSTNSRSG FEMIWDPNGW TGTDSSFSVK QDIVAITDWS GYSGSFVQHP ELTGLDCIRP CFWVELIRGR PKESTIWTSG SSISFCGVNS DTVSWSWPDG AELPFTIDK* Vac2-mc-opt (matrix) (SEQ ID NO: 32) MSLLTEVETY VLSIIPSGPL KAEIAQKLED VFAGKNTDLE ALMEWLKTRP ILSPLTKGIL GFVFTLTVPS ERGLQRRRFV QNALNGNGDP NNMDRAVKLY KKLKREITFH GAKEVSLSYS TGALASCMGL IYNRMGTVTT EVAFGLVCAT CEQIADSQHR SHRQMATITN PLIRHENRMV LASTTAKAME QMAGSSEQAA EAMEVANQAR QMVQAMRTIG THPNSSAGLR DNLLENLQAY QKRMGVQMQR FK*

The synthetic, codon-optimized HA, NA, and M1 genes were subcloned into pFastBac1 transfer plasmid using BamHI and HindIII sites, as described above. Recombinant bacmids for expression in Sf9 cells of synthetic HA, NA, M1 genes were generated as described above, using E. coli strain DH10Bac (Invitrogen).

Example 24 Cloning of Clade 1 A/Viet Nam/1203/04 (H5N1) Influenza Virus by RT-PCR

The HA, NA and M1 genes were cloned by RT-PCR according to the above describes method. The below sequences are comparisons of the published gene compared to the cloned genes.

Comparison of the NA Genes.

Comparisons of the M1 Genes.

All the sequences were cloned and analyzed according to the disclosed methods above.

Example 25 Generation of Clade 1 H5N1 Influenza A/Viet Nam/1203/04 HA, NA, and M1 Genes Optimized for Efficient Expression in Sf9 Cells

The following polypeptides were derived from codon-optimized nucleotides corresponding to A/Viet Nam/1203/04. The nucleotides were designed and synthesized (Geneart GMBH, Regensburg, FRG) as disclosed above (see Example 24).

VN1203-ha-cs-opt (modified cleavage site, underlined) (SEQ ID NO: 33) MEKIVLLFAIVSLVKSDQICIGYHANNSTEQVDTIMEKNVIVTH AQDILEKTHNGKLCDLDGVKPLILRDCSVAGWLLGNPMCDEFINVPEWSYIVEKANPA NDLCYPGDFNDYEELKHLLSRINHFEKIQIIPKNSWSSHEASLGVSSACPYQGKSSFF RNVVWLIKKNNAYPTIKRSYNNINQEDLLVLWGIHHPNDAAEQTRLYQNPITYISVGT STLNQRLVPKIATRSKVNGQNGRMEFFWTILKPNDAINFESNGNFIAPEYAYKIVKKG DSAIMKSELEYGNCNTKCQTPMGAINSSMPFHNIHPLTIGECPKYVKSNRLVLATGLR NSPQRET----RGLFGAIAGFIEGGWQGMVDGWYGYHHSNEQGSGYAADKESTQKAID GVINKVNSIIDKMNTQFEAVGREFNNLERRIENLNKKMEDGFLDVWTYNAELLVLMEN ERTLDFHDSNVKNLYDKVRLQLRDNAKELGNGCFEFYHKCDNECMESVRNGTYDYPQY SEEARLKREEISGVKLESIGTYQILSIYSTVASSLALAIMVAGLSLWMCSNGSLQCRI CI* VN1203-ha-spc-opt (modified signal peptide, underlined) (SEQ ID NO: 34) Mplykllnvlwlvavsnaip DQICIGYHANNSTEQVDTIMEKNVIVTH AQDILEKTHNGKLCDLDGVKPLILRDCSVAGWLLGNPMCDEFINVPEWSYIVEKANPA NDLCYPGDFNDYEELKHLLSRINHFEKIQIIPKNSWSSHEASLGVSSACPYQGKSSFF RNVVWLIKKNNAYPTIKRSYNNINQEDLLVLWGIHHPNDAAEQTRLYQNPITYISVGT STLNQRLVPKIATRSKVNGQNGRMEFFWTILKPNDAINFESNGNFIAPEYAYKIVKKG DSAIMKSELEYGNCNTKCQTPMGAINSSMPFHNIHPLTIGECPKYVKSNRLVLATGLR NSPQRERRRKKRGLFGAIAGFIEGGWQGMVDGWYGYHHSNEQGSGYAADKESTQKAID GVINKVNSIIDKMNTQFEAVGREFNNLERRIENLNKKMEDGFLDVWTYNAELLVLMEN ERTLDFHDSNVKNLYDKVRLQLRDNAKELGNGCFEFYHKCDNECMESVRNGTYDYPQY SEEARLKREEISGVKLESIGTYQILSIYSTVASSLALAIMVAGLSLWMCSNGSLQCRI CI* VN1203-ha-sph9-opt (The signal peptide and cleavage site are italicized) (SEQ ID NO: 35) METISLITIL LVVTASNA DQICIGYHANNSTEQVDTIMEKNVIVTH AQDILEKTHNGKLCDLDGVKPLILRDCSVAGWLLGNPMCDEFINVPEWSYIVEKANPA NDLCYPGDFNDYEELKHLLSRINHFEKIQIIPKNSWSSHEASLGVSSACPYQGKSSFF RNVVWLIKKNNAYPTIKRSYNNINQEDLLVLWGIHHPNDAAEQTRLYQNPITYISVGT STLNQRLVPKIATRSKVNGQNGRMEFFWTILKPNDAINFESNGNFIAPEYAYKIVKKG DSAIMKSELEYGNCNTKCQTPMGAINSSMPFHNIHPLTIGECPKYVKSNRLVLATGLR NSPQRERRRKKRGLFGAIAGFIEGGWQGMVDGWYGYHHSNEQGSGYAADKESTQKAID GVINKVNSIIDKMNTQFEAVGREFNNLERRIENLNKKMEDGFLDVWTYNAELLVLMEN ERTLDFHDSNVKNLYDKVRLQLRDNAKELGNGCFEFYHKCDNECMESVRNGTYDYPQY SEEARLKREEISGVKLESIGTYQILSIYSTVASSLALAIMVAGLSLWMCSNGSLQCRI CI*

Example 26 H5N1 Vietnam/1203/2003 VLP Immunogenicity Extreme Dose Sparing

BALB/C mice were immunized intramuscularly and intranasally with H5N1 VLPs at very low doses of VLPs (0.2, 0.04, 0.008, 0.0016 μg HA/dose), Mice were bled on days 0, 21 and 35. The mice were given a boost on day 21. The serum was assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) using turkey RBCs and influenza virus using an ELISA. Results of this study are shown in FIGS. 24 and 25.

The results indicate that a robust overall immune response was observed when the VLPs were administered intramuscularly at very lose doses. The robustness of the response was similar to control at 3.0 and 0.6 μg HA/dose. These data show see a true dose response and the antibody response to 0.2 μg of VLP is greater than 3.0 μg of rHA protein. Although the response was not as robust for the intranasal administration, a dose of VLPs at 0.2 μg HA/dose did induce a robust response. The ELISA titer with the 0.2 μg dose in this experiment is similar to the 0.12 μg dose of the H3N2 VLP vaccine in previous experiments, see above.

Example 27 Challenge Studies

The results indic After inoculating BALB/c mice with VLPs at concentrations of 3 μg, 0.6 μg 0.12 μg and 0.02 μg of H3N2 VLPs intramuscularly and intranasally (total HA dose), mice were challenged with influenza virus A/Aichi/268x31. The results of this study are shown on FIGS. 27 and 28. These data show that there is a decrease in weight in all vaccinated animals, however the animals that were vaccinated with 3.0 μg and 0.12 μg of VLPs recovered quicker than the other animals in both intramuscular and intranasal vaccinations. The intranasal doses provided enhanced protection.

Example 28 Challenge Studies Ferrets

In this study, ferrets were vaccinated with H9N2 VLPs. There were a total of 18 ferrets in the challenge study: 6 mock vaccinated, 6 vaccinated with medium dose (1.5 μg), and 6 vaccinated with high dose (15.0 μg) intramuscularly. Next, ferrets were challenged with 10⁶ EID₅₀ of A/HK/1073/99 intranasally. Nasal washes were collected on days 1, 3, 5 and 7. The virus in the nasal washes was titered on days 3, 5 and 7 for all animals. These data are represented on Table 2 and in FIG. 29. These data show that by day 7, all of the vaccinated animals had no detectable virus in nasal washes while the mock group had detectable viral titers.

TABLE 2 Wild Type Virus Titers (log 10/ml) in Ferrets after viral challenge Ferret Day 3 Day 5 Day 7 Group: Placebo Mock Control (n = 6) 4512 7 5.5 3.5 4524 6.5 6.75 1.98 4525 7.5 6.5 6.75 4526 7.5 7.25 3.5 4527 6.75 7.25 2.5 4528 7.5 6.25 2.75 Mean 7.125 6.583333 3.496667 Std. 0.44017 0.66458 1.699137 Dev. Group: Low Dose 3916 6.75 2.75 1.5 3917 7.5 5.5 1.5 3918 7.5 6.5 1.5 3919 5.5 3 1.5 3920 6.75 2.25 1.5 3921 6.5 3.5 1.5 Avg 6.75 3.916667 1.5 Std Dev 0.74162 1.693123 0 Group: High Dose 3922 6.5 2.75 1.5 3923 6.25 3.75 1.5 3924 5.75 1.5 1.5 3925 6.5 4.75 1.5 3926 6.25 3.5 1.5 3927 5.75 1.5 1.5 Avg. 6.166667 2.958333 1.5 Std Dev 0.341565 1.298236 0

Example 29 Mice Intramuscular and Intranasal Inoculation Studies

Mice were inoculated with A/Fujian/411/2002 (H3N2) VLPs at concentrations of 3 μg, 0.6 μg 0.12 μg or 0.024 μg (total HA dose) intramuscularly or intranasally at day 0 and were boosted 3 weeks later. Control mice were inoculated with formalin inactivated A/Wyoming (Fujian-Like, vaccine strain) or PBS. Sera were collected from the inoculated mice at weeks 0, 3, 5 and 8. The collected sera were assayed for anti-HA antibodies by the hemagglutination inhibition assay (HI) for anti-influenza antibodies by ELISA. The assay was conducted using A/Fujian/411/2002, A/Panama/2007/99, A/Wyoming/3/03 and A/New York/55/2004 influenza virus strains of H3N2. Results of this study are shown on FIGS. 30 A-H. These data indicate the H3N2 VLPs induced antibodies against the parent A/Fujian/411/2002 strains of influenza virus and against other H3N2 strains. These data also indicate that the titers in intranasally inoculated mice rise later than intramuscularly inoculated mice. However, the intranasal titers are higher than intramuscular titers after about 8 weeks. In addition, titers to the inactivated virus antigen appear to be comparable to the VLP at equivalent doses following intramuscular inoculation. However, the inactivated antigen does not appear to be as immunogenic following intranasal inoculation, nor is it as broadly protective following intranasal inoculation.

Example 30 Generation of Clade 2 H5N1 Influenza HA, NA, and M1 Genes Optimized for Efficient Expression in Sf9 Cells

The following optimized nucleotides and polypeptides corresponding to HA, NA and M1 of Clade 2 H5N1 viruses, A A/Indonesia/5/05, A/Bar headed goose/Qinghai/1A/2005 and A/Anhui/1/2005, were designed and synthesized (Geneart GMBH, Regensburg, FRG) as disclosed above. The optimized nucleotides and polypeptides are listed below. In order to make VLPs, A/Anhui HA can be expressed with A/Indonesia NA and M1. For VLPs comprising A/Quinghai HA and NA, A/Indonesia M1 gene can be co-expressed with A/Quinghai HA and NA.

A/INDONESIA/5/05 A/INDONESIA Optimized HA (Start and stop codon are underlined) (SEQ ID NO: 42) GGTACCGGATCCGCCACCATGGAGAAGATCGTGCTGCTGCTGGCTATCGTGTCCCTGGTG AAGTCCGACCAGATCTGCATCGGTTACCACGCTAACAACTCCACCGAGCAGGTGGACACC ATCATGGAGAAGAACGTCACCGTGACCCACGCTCAGGACATCCTCGAAAAGACCCACAAC GGCAAGCTGTGCGACCTGGACGGTGTCAAGCCCCTGATCCTGCGTGACTGCTCCGTGGCT GGTTGGCTGCTGGGTAACCCCATGTGCGACGAGTTCATCAACGTGCCCGAGTGGTCCTAC ATCGTGGAGAAGGCTAACCCCACCAACGACCTGTGCTACCCCGGTTCCTTCAACGACTAC GAGGAGCTGAAGCACCTGCTGTCCCGTATCAACCACTTCGAGAAGATCCAGATCATCCCC AAGTCCTCTTGGTCCGACCACGAGGCTTCCTCCGGTGTCTCCTCCGCTTGCCCCTACCTG GGTTCCCCCTCCTTCTTCCGTAACGTGGTGTGGCTGATCAAGAAGAACTCCACCTACCCC ACCATCAAGAAGTCCTACAACAACACCAACCAGGAGGACCTGCTGGTCCTGTGGGGTATC CACCACCCCAACGACGCTGCCGAGCAGACCCGTCTGTACCAGAACCCCACCACCTACATC TCCATCGGCACCTCCACCCTGAACCAGCGTCTGGTGCCCAAGATCGCTACCCGTTCCAAG GTGAACGGCCAGTCCGGTCGTATGGAGTTCTTCTGGACCATCCTGAAGCCTAACGACGCT ATCAACTTCGAGTCCAACGGCAACTTCATCGCTCCCGAGTACGCTTACAAGATCGTGAAG AAGGGCGACTCCGCTATCATGAAGTCCGAGCTGGAGTACGGTAACTGCAACACCAAGTGC CAGACCCCCATGGGTGCTATCAACTCCTCCATGCCCTTCCACAACATCCACCCCCTGACC ATCGGCGAGTGCCCCAAGTACGTGAAGTCCAACCGTCTGGTGCTGGCTACCGGTCTGCGT AACTCCCCCCAGCGCGAGTCCCGTCGTAAGAAGCGTGGTCTGTTCGGCGCTATCGCTGGT TTCATCGAGGGCGGTTGGCAGGGCATGGTGGACGGATGGTACGGTTACCACCACTCTAAC GAGCAGGGTTCCGGTTACGCTGCTGACAAGGAGTCCACCCAGAAGGCTATCGACGGCGTC ACCAACAAGGTGAACTCCATCATCGACAAGATGAACACCCAGTTCGAGGCTGTGGGTCGT GAGTTCAACAACCTCGAGCGTCGTATCGAGAACCTGAACAAGAAGATGGAGGACGGTTTC CTGGACGTGTGGACCTACAACGCCGAGCTGCTGGTGCTGATGGAGAACGAGCGTACCCTG GACTTCCACGACTCCAACGTGAAGAACCTGTACGACAAGGTCCGCCTGCAGCTGCGTGAC AACGCTAAGGAGCTGGGTAACGGTTGCTTCGAGTTCTACCACAAGTGCGACAACGAGTGC ATGGAGTCCATCCGTAACGGCACCTACAACTACCCCCAGTACTCCGAGGAGGCTCGTCTG AAGCGTGAGGAGATCTCCGGCGTGAAGCTCGAGTCCATCGGAACCTACCAGATCCTGTCC ATCTACTCCACCGTGGCTTCCTCCCTGGCTCTGGCTATCATGATGGCTGGTCTGTCCCTG TGGATGTGCTCCAACGGTTCCCTGCAGTGCCGTATCTGCATCTAATGAAAGCTTGAGCTC A/INDONESIA HA Protein Sequence (SEQ ID NO: 43) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE SRRKKRGLFG AIAGFIEGGW QGMVDGWYGY HHSNEQGSGY AADKESTQKA IDGVTNKVNS IIDKMNTQFE AVGREFNNLE RRIENLNKKM EDGFLDVWTY NAELLVLMEN ERTLDFHDSN VKNLYDKVRL QLRDNAKELG NGCFEFYHKC DNECMESIRN GTYNYPQYSE EARLKREEIS GVKLESIGTY QILSIYSTVA SSLALAIMMA GLSLWMCSNG SLQCRICI A/INDONESIA Optimized HA (cleavage site deleted) (Start and stop codon are underlined) (SEQ ID NO: 44) GGATCCGCCACCATGGAGAAGATCGTGCTGCTGCTGGCTATCGTGTCCCTGGTGAAGTCC GACCAGATCTGCATCGGTTACCACGCTAACAACTCCACCGAGCAGGTGGACACCATCATG GAGAAGAACGTCACCGTGACCCACGCTCAGGACATCCTCGAAAAGACCCACAACGGCAAG CTGTGCGACCTGGACGGTGTCAAGCCCCTGATCCTGCGTGACTGCTCCGTGGCTGGTTGG CTGCTGGGTAACCCCATGTGCGACGAGTTCATCAACGTGCCCGAGTGGTCCTACATCGTG GAGAAGGCTAACCCCACCAACGACCTGTGCTACCCCGGTTCCTTCAACGACTACGAGGAG CTGAAGCACCTGCTGTCCCGTATCAACCACTTCGAGAAGATCCAGATCATCCCCAAGTCC TCTTGGTCCGACCACGAGGCTTCCTCCGGTGTCTCCTCCGCTTGCCCCTACCTGGGTTCC CCCTCCTTCTTCCGTAACGTGGTGTGGCTGATCAAGAAGAACTCCACCTACCCCACCATC AAGAAGTCCTACAACAACACCAACCAGGAGGACCTGCTGGTCCTGTGGGGTATCCACCAC CCCAACGACGCTGCCGAGCAGACCCGTCTGTACCAGAACCCCACCACCTACATCTCCATC GGCACCTCCACCCTGAACCAGCGTCTGGTGCCCAAGATCGCTACCCGTTCCAAGGTGAAC GGCCAGTCCGGTCGTATGGAGTTCTTCTGGACCATCCTGAAGCCTAACGACGCTATCAAC TTCGAGTCCAACGGCAACTTCATCGCTCCCGAGTACGCTTACAAGATCGTGAAGAAGGGC GACTCCGCTATCATGAAGTCCGAGCTGGAGTACGGTAACTGCAACACCAAGTGCCAGACC CCCATGGGTGCTATCAACTCCTCCATGCCCTTCCACAACATCCACCCCCTGACCATCGGC GAGTGCCCCAAGTACGTGAAGTCCAACCGTCTGGTGCTGGCTACCGGTCTGCGTAACTCC CCCCAGCGCGAGTCCCGTGGTCTGTTCGGCGCTATCGCTGGTTTCATCGAGGGCGGTTGG CAGGGCATGGTGGACGGATGGTACGGTTACCACCACTCTAACGAGCAGGGTTCCGGTTAC GCTGCTGACAAGGAGTCCACCCAGAAGGCTATCGACGGCGTCACCAACAAGGTGAACTCC ATCATCGACAAGATGAACACCCAGTTCGAGGCTGTGGGTCGTGAGTTCAACAACCTCGAG CGTCGTATCGAGAACCTGAACAAGAAGATGGAGGACGGTTTCCTGGACGTGTGGACCTAC AACGCCGAGCTGCTGGTGCTGATGGAGAACGAGCGTACCCTGGACTTCCACGACTCCAAC GTGAAGAACCTGTACGACAAGGTCCGCCTGCAGCTGCGTGACAACGCTAAGGAGCTGGGT AACGGTTGCTTCGAGTTCTACCACAAGTGCGACAACGAGTGCATGGAGTCCATCCGTAAC GGCACCTACAACTACCCCCAGTACTCCGAGGAGGCTCGTCTGAAGCGTGAGGAGATCTCC GGCGTGAAGCTCGAGTCCATCGGAACCTACCAGATCCTGTCCATCTACTCCACCGTGGCT TCCTCCCTGGCTCTGGCTATCATGATGGCTGGTCTGTCCCTGTGGATGTGCTCCAACGGT TCCCTGCAGTGCCGTATCTGCATCTAATGAAAGCTT A/INDONESIA HA Protein sequence (SEQ ID NO: 45) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PTNDLCYPGS FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYLGSPSFF RNVVWLIKKN STYPTIKKSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISIGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI MKSELEYGNC NTKCQTPMGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQRE SRGLFGAIAG FIEGGWQGMV DGWYGYHHSN EQGSGYAADK ESTQKAIDGV TNKVNSIIDK MNTQFEAVGR EFNNLERRIE NLNKKMEDGF LDVWTYNAEL LVLMENERTL DFHDSNVKNL YDKVRLQLRD NAKELGNGCF EFYHKCDNEC MESIRNGTYN YPQYSEEARL KREEISGVKL ESIGTYQILS IYSTVASSLA LAIMMAGLSL WMCSNGSLQC RICI A/INDONESIA Optimized NA (Start and stop codon are underlined) (SEQ ID NO: 46) GGTACCGGATCCGCCACCATGAACCCCAACCAGAAGATCATCACCATCGGCTCCATCTGC ATGGTGATCGGTATCGTGTCCCTGATGCTGCAGATCGGTAACATGATCTCCATCTGGGTG TCCCACTCCATCCAGACCGGTAACCAGCACCAGGCTGAGTCCATCTCCAACACCAACCCC CTGACCGAGAAGGCTGTGGCTTCCGTGACCCTGGCTGGTAACTCCTCCCTGTGCCCCATC CGTGGTTGGGCTGTGCACTCCAAGGACAACAACATCCGCATCGGTTCCAAGGGTGACGTG TTCGTGATCCGTGAGCCCTTCATCTCCTGCTCCCACCTCGAGTGCCGTACCTTCTTCCTG ACCCAAGGTGCTCTGCTGAACGACAAGCACTCCAACGGCACCGTGAAGGACCGTTCCCCC CACCGTACCCTGATGTCCTGCCCCGTGGGCGAGGCTCCCTCCCCCTACAACTCCCGTTTC GAGTCCGTGGCTTGGTCCGCTTCCGCTTGCCACGACGGCACCTCTTGGCTGACCATCGGT ATCTCCGGTCCCGACAACGAGGCTGTCGCTGTGCTGAAGTACAACGGCATCATCACCGAC ACCATCAAGTCCTGGCGTAACAACATCCTGCGTACCCAGGAGTCCGAGTGCGCTTGCGTG AACGGTTCCTGCTTCACCGTGATGACCGACGGTCCCTCCGACGGCCAGGCTTCCTACAAG ATCTTCAAGATGGAGAAGGGCAAGGTGGTGAAGTCCGTGGAGCTGGACGCTCCCAACTAC CACTACGAGGAGTGCTCTTGCTACCCCGACGCTGGCGAGATCACCTGCGTGTGCCGTGAC AACTGGCACGGTTCCAACCGTCCCTGGGTGTCCTTCAACCAGAACCTCGAGTACCAGATC GGTTACATCTGCTCCGGCGTGTTCGGTGACAACCCCCGTCCCAACGACGGAACCGGTTCC TGCGGTCCCATGTCCCCCAACGGTGCTTACGGTGTCAAGGGCTTCTCCTTCAAGTACGGT AACGGTGTCTGGATCGGTCGTACCAAGTCCACCAACTCCCGCTCCGGTTTCGAGATGATC TGGGACCCCAACGGTTGGACCGGCACCGACTCTTCCTTCTCCGTGAAGCAGGACATCGTG GCTATCACCGACTGGTCCGGTTACTCCGGTTCCTTCGTGCAGCACCCCGAGCTGACCGGT CTGGACTGCATTCGTCCCTGCTTCTGGGTGGAGCTGATCCGTGGTCGTCCCAAGGAGTCC ACCATCTGGACCTCCGGCTCCTCCATCTCTTTCTGCGGTGTGAACTCCGACACCGTGTCC TGGTCCTGGCCCGACGGTGCCGAGCTGCCCTTCACCATCGACAAGTAATGAAAGCTTGAG CTC A/INDONESIA NA Protein sequence (SEQ ID NO: 47) MNPNQKIITI GSICMVIGIV SLMLQIGNMI SIWVSHSIQT GNQHQAESIS NTNPLTEKAV ASVTLAGNSS LCPIRGWAVH SKDNNIRIGS KGDVFVIREP FISCSHLECR TFFLTQGALL NDKHSNGTVK DRSPHRTLMS CPVGEAPSPY NSRFESVAWS ASACHDGTSW LTIGISGPDN EAVAVLKYNG IITDTIKSWR NNILRTQESE CACVNGSCFT VMTDGPSDGQ ASYKIFKMEK GKVVKSVELD APNYHYEECS CYPDAGEITC VCRDNWHGSN RPWVSFNQNL EYQIGYICSG VFGDNPRPND GTGSCGPMSP NGAYGVKGFS FKYGNGVWIG RTKSTNSRSG FEMIWDPNGW TGTDSSFSVK QDIVAITDWS GYSGSFVQHP ELTGLDCIRP CFWVELIRGR PKESTIWTSG SSISFCGVNS DTVSWSWPDG AELPFTIDK A/INDONESIA Optimized M1 (SEQ ID NO: 48) GGTACCGGATCCGCCACCATGTCCCTGCTGACCGAGGTGGAGACCTACGTGCTGTCCATC ATCCCCTCCGGTCCTCTGAAGGCTGAGATCGCTCAGAAGCTCGAGGACGTTTTCGCTGGC AAGAACACCGACCTCGAGGCTCTGATGGAGTGGCTCAAGACCCGTCCCATCCTGTCCCCC CTGACCAAGGGTATCCTGGGTTTCGTGTTCACCCTGACCGTGCCCTCCGAGCGTGGTCTG CAGCGTCGTCGTTTCGTGCAGAACGCTCTGAACGGTAACGGTGACCCCAACAACATGGAC CGTGCTGTGAAGCTGTACAAGAAGCTGAAGCGCGAGATCACCTTCCACGGTGCTAAGGAG GTGTCCCTGTCCTACTCCACCGGTGCTCTGGCTAGCTGCATGGGCCTGATCTACAACCGT ATGGGCACCGTGACCACCGAGGTGGCCTTCGGTCTGGTCTGCGCTACCTGCGAGCAGATC GCTGACTCCCAGCACCGTTCCCACCGTCAGATGGCTACCATCACCAACCCCCTGATCCGT CACGAGAACCGTATGGTGCTGGCTTCCACCACCGCTAAGGCTATGGAGCAGATGGCTGGT TCCTCCGAGCAGGCTGCTGAGGCCATGGAGGTGGCCAACCAGGCTCGTCAGATGGTGCAG GCTATGCGTACCATCGGCACCCACCCCAACTCCTCCGCTGGTCTGCGTGACAACCTGCTC GAGAACCTGCAGGCTTACCAGAAGCGTATGGGAGTCCAGATGCAGCGCTTCAAGTAATGA AAGCTTGAGCTC A/INDONESIA M1 Protein sequence (SEQ ID NO: 49) MSLLTEVETY VLSIIPSGPL KAEIAQKLED VFAGKNTDLE ALMEWLKTRP ILSPLTKGIL GFVFTLTVPS ERGLQRRRFV QNALNGNGDP NNMDRAVKLY KKLKREITFH GAKEVSLSYS TGALASCMGL IYNRMGTVTT EVAFGLVCAT CEQIADSQHR SHRQMATITN PLIRHENRMV LASTTAKAME QMAGSSEQAA EAMEVANQAR QMVQAMRTIG THPNSSAGLR DNLLENLQAY QKRMGVQMQR FK A/Anhui/1/2005 A/Anhui Optimized HA (Start and stop codon are underlined) (SEQ ID NO: 50) GGTACCGGATCCCTCGAGATGGAGAAGATCGTGCTGCTGCTGGCTATCGTGTCCCTGGTG AAGTCCGACCAGATCTGCATCGGTTACCACGCTAACAACTCCACCGAGCAGGTGGACACC ATCATGGAGAAGAACGTCACCGTGACCCACGCTCAGGACATCCTGGAAAAGACCCACAAC GGCAAGCTGTGCGACCTGGACGGTGTCAAGCCCCTGATCCTGCGTGACTGCTCCGTGGCT GGTTGGCTGCTGGGTAACCCCATGTGCGACGAGTTCATCAACGTGCCCGAGTGGTCCTAC ATCGTGGAGAAGGCTAACCCCGCTAACGACCTGTGCTACCCCGGTAACTTCAACGACTAC GAGGAGCTGAAGCACCTGCTGTCCCGTATCAACCACTTCGAGAAGATCCAGATCATCCCC AAGTCCTCTTGGTCCGACCACGAGGCTTCCTCCGGTGTCTCCTCCGCTTGCCCATACCAG GGCACCCCATCTTTCTTCCGTAACGTGGTGTGGCTGATCAAGAAGAACAACACCTACCCC ACCATCAAGCGTTCCTACAACAACACCAACCAGGAGGACCTGCTGATCCTGTGGGGTATC CACCACTCCAACGACGCTGCCGAGCAGACCAAGCTGTACCAGAACCCCACCACCTACATC TCCGTGGGCACCTCCACCCTGAACCAGCGTCTGGTGCCCAAGATCGCTACCCGTTCCAAG GTGAACGGCCAGTCCGGTCGTATGGACTTCTTCTGGACCATCCTGAAGCCTAACGACGCT ATCAACTTCGAGTCCAACGGCAACTTCATCGCTCCCGAGTACGCTTACAAGATCGTGAAG AAGGGCGACTCCGCTATCGTCAAGTCCGAGGTGGAGTACGGTAACTGCAACACCAAGTGC CAGACCCCCATCGGTGCTATCAACTCCTCCATGCCCTTCCACAACATCCACCCCCTGACC ATCGGCGAGTGCCCCAAGTACGTGAAGTCCAACAAGCTGGTGCTGGCTACCGGTCTGCGT AACTCCCCCCTGCGTGAGCGTGGTCTGTTCGGCGCTATCGCTGGTTTCATCGAGGGCGGT TGGCAGGGCATGGTGGACGGTTGGTACGGTTACCACCACAGCAACGAGCAGGGTTCCGGT TACGCTGCTGACAAGGAGTCCACCCAGAAGGCTATCGACGGCGTCACCAACAAGGTGAAC TCCATCATCGACAAGATGAACACCCAGTTCGAGGCTGTGGGTCGTGAGTTCAACAACCTG GAGCGTCGTATCGAGAACCTGAACAAGAAGATGGAGGACGGTTTCCTGGACGTGTGGACC TACAACGCCGAGCTGCTGGTGCTGATGGAGAACGAGCGTACCCTGGACTTCCACGACTCT AACGTGAAGAACCTGTACGACAAGGTCCGCCTGCAGCTGCGTGACAACGCTAAGGAGCTG GGTAACGGTTGCTTCGAGTTCTACCACAAGTGCGACAACGAGTGCATGGAGTCCGTGCGT AACGGCACCTACGACTACCCCCAGTACTCCGAGGAGGCTCGTCTGAAGCGTGAGGAGATC TCCGGCGTGAAGCTGGAGTCCATCGGCACCTACCAGATCCTGTCCATCTACTCCACCGTG GCTTCCTCCCTGGCTCTGGCTATCATGGTGGCTGGTCTGTCCCTGTGGATGTGCTCCAAC GGTTCCCTGCAGTGCCGTATCTGCATCTAATAATGAGGCGCGCCAAGCTTGAGCTC A/Anhui HA Protein sequence (SEQ ID NO: 51) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFINVP EWSYIVEKAN PANDLCYPGN FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYQGTPSFF RNVVWLIKKN NTYPTIKRSY NNTNQEDLLI LWGIHHSNDA AEQTKLYQNP TTYISVGTST LNQRLVPKIA TRSKVNGQSG RMDFFWTILK PNDAINFESN GNFIAPEYAY KIVKKGDSAI VKSEVEYGNC NTKCQTPIGA INSSMPFHNI HPLTIGECPK YVKSNKLVLA TGLRNSPLRE RGLFGAIAGF IEGGWQGMVD GWYGYHHSNE QGSGYAADKE STQKAIDGVT NKVNSIIDKM NTQFEAVGRE FNNLERRIEN LNKKMEDGFL DVWTYNAELL VLMENERTLD FHDSNVKNLY DKVRLQLRDN AKELGNGCFE FYHKCDNECM ESVRNGTYDY PQYSEEARLK REEISGVKLE SIGTYQILSI YSTVASSLAL AIMVAGLSLW MCSNGSLQCR ICI A/Bar headed goose/Qinghai/1A/2005 A/Qinghai Optimized HA (Start and stop codon are underlined) (SEQ ID NO: 52) CGGGCGCGGAGCGGCCGCATGGAGAAGATCGTGCTGCTGCTGGCTATCGTGTCTCTGGTCAAGTCCGACCAGATCTGCA TCGGTTACCACGCTAACAACTCCACCGAGCAGGTGGACACCATCATGGAGAAGAACGTCACCGTGACCCACGCTCAGGA CATCCTCGAAAAGACCCACAACGGCAAGCTGTGCGACCTGGACGGCGTGAAGCCCCTGATCCTGCGTGACTGCTCCGTG GCTGGTTGGCTGCTGGGTAACCCCATGTGCGACGAGTTCCTCAACGTGCCCGAGTGGTCCTACATCGTGGAGAAGATCA ACCCCGCTAACGACCTGTGCTACCCCGGTAACTTCAACGACTACGAGGAGCTGAAGCACCTGCTGTCCCGTATCAACCA CTTCGAGAAGATCCAGATCATCCCCAAGTCCTCTTGGTCCGACCACGAGGCTTCCTCCGGTGTCTCCTCCGCTTGCCCA TACCAGGGCCGTTCTTCCTTCTTCCGCAACGTGGTGTGGCTGATCAAGAAGAACAACGCCTACCCCACCATCAAGCGTT CCTACAACAACACCAACCAGGAGGACCTGCTGGTCCTGTGGGGTATCCACCACCCCAACGACGCTGCCGAGCAGACCCG TCTGTACCAGAACCCCACCACCTACATCTCCGTGGGCACCTCTACCCTGAACCAGCGTCTGGTGCCCAAGATCGCTACC CGTTCCAAGGTGAACGGCCAGTCCGGTCGTATGGAGTTCTTCTGGACCATCCTGAAGCCTAACGACGCTATCAACTTCG AGTCCAACGGCAACTTCATCGCTCCCGAGAACGCTTACAAGATCGTGAAGAAGGGCGACTCCACCATCATGAAGTCCGA GCTGGAGTACGGCAACTGCAACACTAAGTGCCAGACCCCCATCGGTGCTATCAACTCCTCCATGCCCTTCCACAACATC CACCCCCTGACTATCGGCGAGTGCCCCAAGTACGTGAAGTCCAACCGTCTGGTGCTGGCTACCGGTCTGCGTAACTCCC CCCAGATCGAGACTCGTGGTCTGTTCGGCGCTATCGCTGGTTTCATCGAGGGCGGTTGGCAGGGCATGGTGGACGGTTG GTACGGTTACCACCACTCTAACGAGCAGGGTTCCGGTTACGCTGCTGACAAGGAGTCTACCCAGAAGGCTATCGACGGC GTCACCAACAAGGTGAACTCCATCATCGACAAGATGAACACCCAGTTCGAGGCTGTGGGTCGTGAGTTCAACAACCTCG AACGTCGTATCGAGAACCTGAACAAGAAGATGGAGGACGGTTTCCTGGACGTGTGGACCTACAACGCCGAGCTGCTGGT GCTGATGGAGAACGAGCGTACCCTGGACTTCCACGACTCCAACGTGAAGAACCTGTACGACAAGGTCCGCCTGCAGCTG CGTGACAACGCTAAGGAGCTGGGTAACGGTTGCTTCGAGTTCTACCACCGTTGCGACAACGAGTGCATGGAGTCCGTGC GTAACGGCACCTACGACTACCCCCAGTACTCCGAGGAGGCTCGTCTGAAGCGTGAGGAGATCTCCGGTGTCAAGCTCGA ATCCATCGGAACCTACCAGATCCTGTCCATCTACTCCACCGTGGCTTCCTCCCTGGCTCTGGCTATCATGGTGGCTGGT CTGTCCCTGTGGATGTGCTCCAACGGTTCCCTGCAGTGCCGTATCTGCATCTAATAATGAGGCGCGCCAAGCTTGTCGA A/Qinghai HA Protein sequence (SEQ ID NO: 53) MEKIVLLLAI VSLVKSDQIC IGYHANNSTE QVDTIMEKNV TVTHAQDILE KTHNGKLCDL DGVKPLILRD CSVAGWLLGN PMCDEFLNVP EWSYIVEKIN PANDLCYPGN FNDYEELKHL LSRINHFEKI QIIPKSSWSD HEASSGVSSA CPYQGRSSFF RNVVWLIKKN NAYPTIKRSY NNTNQEDLLV LWGIHHPNDA AEQTRLYQNP TTYISVGTST LNQRLVPKIA TRSKVNGQSG RMEFFWTILK PNDAINFESN GNFIAPENAY KIVKKGDSTI MKSELEYGNC NTKCQTPIGA INSSMPFHNI HPLTIGECPK YVKSNRLVLA TGLRNSPQIE TRGLFGAIAG FIEGGWQGMV DGWYGYHHSN EQGSGYAADK ESTQKAIDGV TNKVNSIIDK MNTQFEAVGR EFNNLERRIE NLNKKMEDGF LDVWTYNAEL LVLMENERTL DFHDSNVKNL YDKVRLQLRD NAKELGNGCF EFYHRCDNEC MESVRNGTYD YPQYSEEARL KREEISGVKL ESIGTYQILS IYSTVASSLA LAIMVAGLSL WMCSNGSLQC RICI A/Qinghai Optimized NA (Start and stop codon are underlined) (SEQ ID NO: 54) ACCGTCCCACCATCGGGCGCGGATCCCTCGAGATGAACCCCAACCAGAAGATCATCACCATCGGCTCCATCTGCATGGT GATCGGTATCGTGTCCCTGATGCTGCAGATCGGTAACATGATCTCCATCTGGGTGTCCCACTCCATCCAGACCGGTAAC CAGCGTCAGGCCGAGCCCATCTCCAACACCAAGTTCCTCACCGAGAAGGCTGTGGCTTCCGTGACCCTGGCTGGTAACT CCTCCCTGTGCCCCATCTCCGGTTGGGCTGTGTACTCCAAGGACAACTCCATCCGTATCGGTTCCCGTGGTGACGTGTT CGTGATCCGTGAGCCCTTCATCTCCTGCTCCCACCTCGAATGCCGTACCTTCTTCCTGACCCAGGGTGCTCTGCTGAAC GACAAGCACTCCAACGGCACCGTGAAGGACCGTTCCCCCCACCGTACCCTGATGTCCTGCCCCGTGGGCGAGGCTCCCT CCCCCTACAACTCCCGTTTCGAGTCCGTGGCTTGGTCCGCTTCCGCTTGCCACGACGGCACCTCTTGGCTGACCATCGG TATCTCCGGTCCCGACAACGGTGCTGTGGCTGTGCTGAAGTACAACGGCATCATCACCGACACCATCAAGTCCTGGCGT AACAACATCCTGCGTACCCAAGAGTCCGAGTGCGCTTGCGTGAACGGTTCCTGCTTCACCGTGATGACCGACGGTCCCT CCAACGGCCAGGCTTCCTACAAGATCTTCAAGATGGAGAAGGGCAAGGTGGTGAAGTCCGTGGAGCTGGACGCTCCCAA CTACCACTACGAGGAGTGCTCTTGCTACCCCGACGCTGGCGAGATCACCTGCGTGTGCCGTGACAACTGGCACGGTTCC AACCGTCCCTGGGTGTCCTTCAACCAGAACCTCGAATACCAGATCGGTTACATCTGCTCCGGCGTGTTCGGTGACAACC CCCGTCCCAACGACGGAACCGGTTCCTGCGGTCCCGTGTCCCCCAACGGTGCTTACGGTGTCAAGGGCTTCTCCTTCAA GTACGGTAACGGTGTCTGGATCGGTCGTACCAAGTCCACCAACTCCCGCTCCGGTTTCGAGATGATCTGGGACCCCAAC GGTTGGACCGGCACCGACTCTTCCTTCTCCGTGAAGCAGGACATCGTGGCTATCACCGACTGGTCCGGTTACTCCGGTT CCTTCGTGCAGCACCCCGAGCTGACCGGTCTGGACTGTATCCGTCCCTGCTTCTGGGTGGAGCTGATCCGTGGTCGTCC CAAGGAGTCCACCATCTGGACCTCCGGCTCCTCCATCTCTTTCTGCGGTGTGAACTCCGACACCGTGTCCTGGTCCTGG CCCGACGGTGCCGAGCTGCCCTTCACCATCGACAAGTAATAATGAATCGATTTGTCGAGAAGTACTAGAGGATCATAAT Protein sequence: A/Qinghai NA Protein sequence (SEQ ID NO: 55) MNPNQKIITI GSICMVIGIV SLMLQIGNMI SIWVSHSIQT GNQRQAEPIS NTKFLTEKAV ASVTLAGNSS LCPISGWAVY SKDNSIRIGS RGDVFVIREP FISCSHLECR TFFLTQGALL NDKHSNGTVK DRSPHRTLMS CPVGEAPSPY NSRFESVAWS ASACHDGTSW LTIGISGPDN GAVAVLKYNG IITDTIKSWR NNILRTQESE CACVNGSCFT VMTDGPSNGQ ASYKIFKMEK GKVVKSVELD APNYHYEECS CYPDAGEITC VCRDNWHGSN RPWVSFNQNL EYQIGYICSG VFGDNPRPND GTGSCGPVSP NGAYGVKGFS FKYGNGVWIG RTKSTNSRSG FEMIWDPNGW TGTDSSFSVK QDIVAITDWS GYSGSFVQHP ELTGLDCIRP CFWVELIRGR PKESTIWTSG SSISFCGVNS DTVSWSWPDG AELPFTIDK

Example 31 Human Administration of H5N1 VLPs Vaccines

The purpose of this double-blind, placebo-controlled study was to evaluate the reactogenicity and immunogenicity of H5N1 VLP influenza vaccine (H5N1 VLP) in healthy adults 18 to 40 years of age. The study design evaluates approximately 230 subjects.

Approximately 70 subjects received two doses of a vaccine comprising H5N1 VLPs at a dosage of either 15 μg or 45 μg (or placebo). Of the 70 subjects who were enrolled in this study, 20 subjects where in the 15 μg arm and 50 subjects were in the 45 μg arm. Dosing commenced at 15 μg, which is approximately one third of the total HA antigen content targeted for most seasonal influenza vaccines. Subjects were randomly assigned to receive either two doses (day 0 and day 28) of vaccine or placebo in a 7:3 ratio.

The H5N1 VLP vaccine (H5N1 VLP) used in this study was comprised of virus-like particles (VLPs) containing the hemagglutinin (HA), neuraminidase (NA), and matrix 1 (M1) proteins derived from A/Indonesia/05/2005 (H5N1) influenza virus, which had been extracted and purified from Spodoptera frugiperda (Sf9) insect cells infected with a recombinant baculovirus containing the influenza virus genes for HA, NA, and M1. The 45 μg dosages were packaged in single-dose vials, with 0.5 mL dose of the vaccine formulated to contain 45 μg of HA in phosphate buffered saline with 0.5M NaCl at neutral pH. The 15 μg dose was prepared by the clinical site pharmacist by 5:1 dilution of placebo (phosphate buffered saline with 0.5M NaCl at neutral pH) and 180 μg/ml vaccine according to a standard procedure. The H5N1 VLP vaccine was administered by IM injection in the deltoid muscle.

Blood samples for the evaluation were collected at baseline (pre dose 1), approximately 4 weeks later (post dose 1/pre dose 2), approximately 4 weeks post dose 2 and approximately 6 months post dose two. Hemagglutination-inhibition titers and viral neutralization titers were measured utilizing the assays described above. The viruses used for the neutralization studies were wild type, egg-adapted, A/Indo/5/2005 and A/Vietnam/1203/04. Results from this study are shown in the tables below.

TABLE 3 Subject Accounting for Immunogenicity Analyses 15 μg 45 μg 45 μg HAI & Neut HAI Neut (N = 14) (N = 35) (N = 35) Status n (%) n (%) n (%) Randomized 14 (100) 35 (100) 35 (100) Discontinued  1 (7.1)  2 (5.7)  2 (5.7) Samples/  1 (7.1)  2 (5.7)  3 (8.6) results missing Evaluable 12 (85.7) 31 (88.6) 30 (85.7) samples

Table 4 summarizes the data of neutralizing antibody titers against A/Indo/5/2005 among subjects who received two doses of the H5N1 VLP vaccine at a dose of 15 μg. Three values for neutralizing antibody titers were available for each subject.

TABLE 4 Neutralizing Antibody Titers Against A/Indo/5/2005 (15 μg) Subject # Run #1* Run #2* Run #3* GMT 1 5 10 10 7.9 2 20 20 10 15.9 3 10 10 10 10.0 4 20 10 10 12.6 5 10 10 10 10.0 6 10 10 10 10.0 7 5 5 5 5.0 8 40 80 40 50.4 9 10 5 10 7.9 10  40 40 20 31.7 11  5 5 5 5.0 12  5 5 5 5.0 Group 11.2 11.2 10.0 10.8 GMT *Run 1 - passed; Run 2 - plate failure and TCID₅₀ titer for Indonesia virus was outside of set range; Run 3 - controls failed but TCID₅₀ titer within range; Results for all 3 runs were consistent (within 2-fold)

Table 5 summarizes hemagglutination inhibition (HAI) from individuals who received two doses of the of the H5N1 VLP vaccine at a dose of 45 μg.

TABLE 5 HAI Responses* (VLP Vaccine at 45 μg) n (%) HAI against HAI against Immunologic A/Indo/5/05 A/VN/1203/04 Parameter N = 31 N = 31 Titer ≧1:10 17 (55) 4 (13) Titer ≧1:20 15 (48) 3 (10) Titer ≧1:40 10 (32) 2 (7) 4-fold rise from 15 (48) 3 (10) baseline GMT (95% CI) 14.6 (9.8, 21.9) 6.4 (4.9, 8.4) *No subjects had detectable antibody at baseline No placebo recipients had detectable antibody

Table 6 summarizes neutralizing antibody responses among subjects who received two doses of the H5N1 VLP vaccine at a dose of 45 μg.

TABLE 6 Neutralizing Antibody Responses* n (%) Neut. Antibody Neut. Antibody against against Immunologic A/Indo/5/05 A/VN/1203/04 Parameter N = 30 N = 30 Titer ≧1:10 25 (83) 5 (17) Titer ≧1:20 19 (63) 0 (0) Titer ≧1:40 14 (47) 0 (0) 4-fold rise from 19 (63) 0 (0) baseline GMT (95% CI) 32.8 (21.3, 50.6) 5.7 (5.1, 6.4) *No subjects had detectable antibody at baseline. No placebo recipients had detectable antibody.

These data show that among healthy adults who received two injections of H5N1 VLP influenza vaccine at a dose of 15 μg, there was an induction immunologic activity (neutralizing antibody) against the homologous A/Indo/5/05 influenza strain (Table 4). In addition, a vaccine dose of 45 μg was immunogenic with respect to HAI and neutralizing antibody responses against the homologous A/Indo/5/05 influenza strain (Tables 5 and 6). Moreover, antibody responses against the A/Viet Nam/1203/04 strain were observed in a limited number of subjects. Thus, these data show that administering influenza VLPs of the invention to a human can induce a protective (HAI Titer ≧1:40) immune response.

Example 32 Expressing Seasonal and Avian VLPs from Two Baculovirus Vectors

Seasonal and avian influenza M1 and HA proteins were cloned and expressed in a baculovirus expression system. In this example, the A/Indonesia/5/05 was cloned into a one baculovirus and the HA and/or NA was cloned in another baculovirus vector. Both viruses were co infected into Sf9 insect cells and grown under conditions that allow VLP formation. Cells comprising either seasonal HA and M1, avian HA and M1 or a combination of seasonal and avian HA and M1 were grown under conditions that allow formation of VLPs. The seasonal influenza strains used for these experiments were A/Fujian/411/2002 and A/Wisconsin/67/2005 and the avian influenza strain used was A/Indonesia/5/05.

Next, the VLPs were harvested and isolated from the supernatant by centrifugation and by a discontinuous sucrose step gradient. The fraction comprising the VLPs was collected from the top of the gradient. The VLPs isolated from the sucrose gradient were analyzed by SDS-PAGE and western immunoblot. These data are on illustrated on FIGS. 1 and 2.

FIG. 31 is a stained SDS-PAGE gel. The lanes in the gel comprise the following: 1 to 5, A/Fujian M1 with 4 different HAs or alone; 6 to 10, A/Indo/M1 with 4 different HAs or alone; 11 to 14, various controls.

Comparing the bands on the gel, the lanes that comprise VLPs comprising avian M1 have stronger bands of M1 and HA in the same lanes, while the lanes that comprise seasonal influenza do not. M1 and HA bands in the same lane is indicative of HA associating with M1. This association is indicative of VLP formation comprising HA and M1. These data provide evidence that avian influenza proteins form VLPs more efficiently than seasonal influenza M1 either with homologous or heterologous envelopes. These data also show that M1 from avian influenza is strongly expressed and stable when compared to seasonal influenza M1.

FIG. 32 is a western blot showing M1 expression. This blot shows that avian influenza M1 is strongly expressed as compared to seasonal M1. The intensity of the bands indicate that there is more M1, and thus, more VLPs.

Example 33 Expressing Seasonal and Avian VLPs from One Baculovirus Vector

Seasonal and avian influenza M1 and HA proteins were cloned and expressed in a baculovirus expression system. This example, the A/Indonesia/5/05 M1 and A/Fujian/411/2002 HA and NA was cloned into a one baculovirus vector. The recombinant virus was infected into Sf9 insect cells and grown under conditions that allow VLP formation. Cells comprising either seasonal HA and M1, avian HA and M1 or a combination of seasonal and avian HA and M1 were grown under conditions that allow formation of VLPs. The seasonal influenza strains used for these experiments were A/Fujian/411/2002 and A/Wisconsin/67/2005 and the avian influenza strain used was A/Indonesia/5/05.

Next, VLPs were harvested and isolated from the supernatant by centrifugation and by a discontinuous sucrose step gradient. The fraction comprising the VLPs was collected from the top of the gradient. The VLPs isolated from the sucrose gradient were analyzed by SDS-PAGE and western immunoblot. These data are on illustrated on FIGS. 3 and 4.

FIG. 33 is a stained SDS-PAGE gel. The lanes in the gel comprise the following: 1 and 2 is A/Fujian VLPS (M1, HA and NA) and lane 3 comprises, A/Indo/M1 with A/Fujian HA and NA.

Comparing the bands on the gel, the lane that comprise VLPs from A/Indo/M1 has stronger bands of M1 and HA in the same lanes, while the lanes that comprise A/Fujian do not. M1, HA and NA bands in the same lane is indicative of HA and NA associating with M1. This association is indicative of VLP formation comprising HA, NA, and M1. These data provide evidence that avian influenza proteins form VLPs with greater efficiency than seasonal M1 influenza based VLPs. These data also show that M1 from avian influenza is strongly expressed and stable when compared to seasonal influenza M1.

FIG. 34 is a western blot showing M1 expression. This blot shows that VLPs comprising endo A/Indo/M1 and A/Fujian HA, NA are strongly expressed as compared to A/Fujian VLPs. The intensity of the bands indicate that there is more M1, HA and NA in lanes with avian M1 VLPs, and thus, more VLPs.

Example 34 Expressing Chimeric Influenza B HA and NA Constructs Using Common A/Indonesia/5/05 Matrix Protein to Assemble VLPs

The sequences below depict the transmembrane and terminal sequences derived from A/Indonesia/5/05 HA and NA (underlined). The transmembrane and terminal sequences of HA and NA molecules can be determined using software prediction by GCG/Accelrys or similar software, as well as by other methods. The exact location of junctions for Indonesia/5/05 sequences can vary.

The sequences below are examples of a chimeric B strain HA with an A/Indonesia/5/05 HA end as well as a chimeric B strain NA with an A/Indo NA substitution of the endodomain and transmembrane regions. These sequences are co-expressed in a baculovirus expression system with an avian influenza M1 protein to produce chimeric VLPs that express influenza B antigens on the surface of VLPs.

Hemagglutinin, HA, from Influenza B virus (B/Hong Kong/557/2000) ABL76892 (SEQ ID NO: 78)   1 mkaiivllmv vtsnadrict gitssnsphv vktatqgevn vtgviplttt ptkshfanlk  61 gtrtrgklcp dclnctdldv algrpmcvgt tpsakasilh evrpvtsgcf pimhdrtkir 121 qlpnllrgye nirlstqnvi daekapggpy rlgtsgscpn atsksgffat mawavpkdnn 181 knatnpltve vpyvcteged qitvwgfhsd nktqmknlyg dsnpqkftss angvtthyvs 241 qiggfpdqte dgglpqsgri vvdymvqkpg ktgtivyqrg vllpqkvwca sgrskvikgs 301 1pligeadcl hekygglnks kpyytgehak aigncpiwvk tplklangtk yrppakllke 361 rgffgaiagf leggwegmia gwhgytshga hgvavaadlk stqeainkit knlnslsele 421 vknlqrlsga mdelhneile ldekvddlra dtissqiela vllsnegiin sedehllale 481 rklkkmlgps avdigngcfe tkhkcnqtcl driaagtfna gefslptfds lnitaaslnd 541 dgldnhtQIL SIYSTVASSL ALAIMMAGLS LWMCSNGSLQ CRICI Neuraminidase, NA, from Flu B/Shanghai/361/02 ISDN129538 (SEQ ID NO: 79) MNPNQKIITIGSICMVIGIVSLMLQIGNMISSDILLKFSTTEITAPTMPLDCANASNVQAVNRSATKGVTLLLPE PEWTYPRLSCPGSTFQKALLISPHRFGETKGNSAPLIIREPFIACGPKECKHFALTHYAAQPGGYYNGTREDRNK LRHLISVKLGKIPTVENSIFHMAAWSGSACHDGKEWTYIGVDGPDSNALLKIKYGEAYTDTYHSYANNILRTQES ACNCIGGNCYLMITDGSASGISECRFLKIREGRIIKEIFPTGRVKHTEECTCGFASNKTIECACRDNSYTAKRPF VKLNVETDTAEIRLMCTETYLDTPRPDDGSITGPCESNGNKGSGGIKGGFVHQRMASKIGRWYSRTMSKTKRMGM GLYVKYDGDPWIDSDALALSGVMVSMEEPGWYSFGFEIKDKKCDVPCIGIEMVHDGGKETWHSAATAIYCLMGSG QLLWDTVTGVDMAL M1 from A/Indonesia (SEQ ID NO: 49) MSLLTEVETY VLSIIPSGPL KAEIAQKLED VFAGKNTDLE ALMEWLKTRP ILSPLTKGIL GFVFTLTVPS ERGLQRRRFV QNALNGNGDP NNMDRAVKLY KKLKREITFH GAKEVSLSYS TGALASCMGL IYNRMGTVTT EVAFGLVCAT CEQIADSQHR SHRQMATITN PLIRHENRMV LASTTAKAME QMAGSSEQAA EAMEVANQAR QMVQAMRTIG THPNSSAGLR DNLLENLQAY QKRMGVQMQR FK

Example 35 Making Chimeric VLPs with Coronavirus S Protein Materials and Methods

Spodoptera frugiperda Sf9 insect cells (ATCC CRL-1711) were maintained as suspension in HyQ-SFX insect serum free medium (HyClone, Logan, Utah) at 28° C. A Bac-to-Bac baculovirus expression system (Invitrogen, Carlsbad, Calif.) was used with pFastBac 1 transfer vector in E. coli DH10Bac cells for the generation of recombinant baculovirus vectors expressing SARS S and Influenza M1 genes.

SARS coronavirus (SARS-CoV) Urbani strain spike (S) protein amino acids sequence was obtained from NCBI access number AAP13441. The hemagglutinin amino acids sequence of influenza A virus (A/Indonesia/5/05(H5N1)) was obtained from NCBI access number ABP51969. To construct the chimeric SARS S protein, the transmembrane and carboxyl terminal domain (TM/CT) of S protein (aa 1196-1255) was removed, and the TM/CT from Indonesia H5N1 HA (aa 531-568) was added after amino acid 1195 of S protein. The amino acids sequence of the chimeric S-HA protein is shown in FIG. 35 (SEQ ID NO: 62). The matrix protein 1 (M1) amino acids sequence of influenza Indonesia H5N1 was obtained from NCBI access number ABW06359 (FIG. 36).

The codon optimized DNA sequences of M1 and chimeric S for expression in insect cells were synthesized by Geneart (Germany) and subcloned into BamHI and HindIII sites of pFastBac 1 individually. The SnaBI/PuvI fragment containing M1 coding sequence of pFastBac1-M1 was cut and inserted into the HpaI/PvuI fragment containing S coding sequence from pFastBac1-S. The result tandem vector that expresses two proteins is shown in FIG. 37. This vector was used to transform DH10Bac to obtain the bacmid which was tranfected into Sf9 cell to obtain the recombinant baculovirus.

VLPs Expression, Purification and Characterizations

Sf9 insect cells were infected for 64 hours at a cell density of 2×10⁶ cells/ml with recombinant baculoviruses that express both chimeric SARS S and Indo M1 at a MOI=1. Culture supernatants were harvest by centrifuge at 4000 g. The cell free supernatants were concentrated by ultrafiltration (UF) with a 500 kDa MWCO hollow fiber filter (GE healthcare). The retentate was buffer exchanged with diafiltration (DF) to 25 mM TrisCl pH 8.0, 300 mM NaCl. The UF/DF retentate was loaded on an ion exchange column (Fractogel TMAE, EMD) equilibrium in the same buffer. VLPs passed through from the column while baculovirus and DNA bound to the column. The flow through fractions containing VLPs were further concentrated with ultrafiltration before load to a Sephacryl S500 size exclusion column (GE healthcare).

The pool of VLPs peak from size exclusion column was analyzed with SDS-PAGE (4-12% Bis-Tris NuPage, Invitrogen) and densitometry for purity. The VLPs were also analyzed with particle size analyzer (Malvern Zetasizer NanoSeries NanoZS) and electron microscopy. The antibodies used in this study were from the following vendors: rabbit anti-SARS S and normal anti-rabbit IgG (IMGNEX), rabbit anti-SARS M (Abgent), mouse anti-influenza M1 (Serotec).

Results

Purified SARS S/Indo M1 chimeric VLPs were analyzed by SDS-PAGE, densitometry and western blot (FIG. 38). The purity for SARS S protein was 13.7% and purity for Indo M1 protein was 67.6%. The combined purity for the S and M1 is 81.3%. The western blot confirmed the identity of S and M1 (FIG. 38, lane 2).

Recombinant baculovirus that expressed SARS spike (S), membrane (M) and envelope (E) proteins in a tandem manner were also expressed. We expressed and purified the wild type SARS VLPs with the same protocol that was used to purify chimeric VLPs. The purity of wild type SARS VLPs (no influenza proteins) were analyzed by SDS-PAGE and western blot (FIG. 39). The S and M proteins can hardly be seen in the Coomassie-stained gel and the contaminant proteins were much more prominent. The data indicate that wild type SARS VLPs are insufficient to form in the baculovirus insect cell expression system while the SARS S/Indo M1 chimeric VLPs an greatly improve the yield and purity of the product VLPs.

Next, we analyzed the average particle size of purified chimeric VLPs to be 159.2 nm (FIG. 40). The chimeric VLPs were imaged with electron microscopy (EM) negative stain (FIG. 41). The size and morphology of chimeric VLPs are very similar to the published EM images of SARS coronavirus (FIG. 42). They are about 100 nm diameter with corona structure on the outer rim. The immuno-gold EM with anti-SARS S antibody confirmed that SARS S proteins were located on the surface of chimeric VLPs (FIG. 12).

The inventors have engineered a chimeric VLP comprising the major spike (S) gene of coronavirus (CoV) that causes SARS. A CoV S chimeric envelope glycoprotein was made by replacing the transmembrane and C-terminus (endodomain) with analogous sequences from the avian influenza HA (A/Indonesia/5/05 H5N1 strain). Unexpected high levels of SARS VLPs were produced in Sf9 insect cells infected with a baculovirus expressing the chimeric SARS S glycoprotein and the avian M1 matrix protein. Chimeric VLPs comprising S protein have the morphology that is nearly identical to the wild type CoV with the recombinant, chimeric S spike protein forming a corona (crown)-envelope in a lipid envelope on spherical particles with an avian influenza M1 core. These recombinant chimeric SARS-avian flu VLPs are efficiently produced in insect cells and were purified as described above.

These data provide an excellent example that avian M1, e.g. Indonesia H5N1 M1 protein, can form chimeric VLPs with surface antigen from other virus such as SARS-CoV. The chimeric VLPs with avian influenza protein as backbone can be purified through a manufacturing friendly procedure that requires only two steps of chromatography. The size and morphology of the chimeric VLPs are similar to the wild type viruses that carry the same surface antigen.

Example 36 Chimeric Influenza B VLPs

Influenza B virus antigen is an important component of seasonal influenza vaccines. The expression levels of influenza B antigen are critically important for ensuring timely delivery of sufficient number of influenza vaccine doses, otherwise vaccine shortages can occur. Influenza B VLPs for B/Florida/4/06 consist of three proteins, HA (SEQ ID NO: 73), NA (SEQ ID NO: 68), and M1 (SEQ ID NO: 77), which are assembled into VLP structure. HA and NA genes where obtained by RT-PCR from the influenza B/Florida/4/06 virus. In order to improve expression levels of influenza B VLPs, VLPs using three different M1 proteins were made. One M1 protein is derived from the B/Florida/4/06 virus. The second M1 gene is derived from influenza B/Ann Arbor/1/1986 strain, which is often used for preparation of live reassortant influenza B viruses in current influenza vaccine industry. The third M1 is derived from avian influenza A/Indonesia/5/05 (H5N1) virus. Thus, three types of influenza B/Florida/4/06 VLPs have been produced in Sf9 cells, and expression levels have been compared.

Methods. Baculoviruses were engineered to express full length HA, NA, and M1 genes of influenza. HA and NA genes where obtained by RT-PCR from the influenza B/Florida/4/06 virus. M1 gene has been also generated by RT-PCR from the influenza B/Florida/4/06 virus. Alternatively, M1 gene of B/Ann Arbor/1/1986 was synthesized (GeneArt, Germany) and M1 gene of influenza A/Indonesia/5/05 (H5N1) was also synthesized (GeneArt, Germany). Each gene was cloned into a pFastBac1 vector under the control of the baculovirus polyhedrin promoter (Invitrogen). Then, HA, NA, and M1 genes were combined into tandem vectors as shown on FIG. 43. Then, tandem gene constructs were transferred to an AcMNPV baculovirus bacmid vectors (Invitrogen), the Bacmid DNAs were purified and used to transfect Sf9 insect cells. The resulting recombinant baculoviruses were plaque-purified and virus stocks prepared in Sf9 cells.

About 30 ml of Sf9 cells, at about 2×10⁶ cells/ml in a 125 ml shaker flasks, were infected with recombinant baculoviruses expressing HA, NA, and M1 genes at a multiplicity of infection (MOI) of 1-3 infectious particles per ml (pfu), incubated at 27° C. with constant shaking, then harvested at 66-72 hours post infection. The media was removed by low speed centrifugation. Then, media were clarified using filtration through 0.45 μM filters and the media were subjected to ultracentrifugation for 1 hour at 26,000 rpm through 30% sucrose layer. Pellets were resuspended in 200 ml of PBS and analyzed by SDS-PAGE and western blot (FIG. 14). Resuspended pellets were also analyzed for ability to agglutinate guinea pig red blood cells in vitro. The data are shown on FIG. 44. The resuspended pellets have been also analyzed by negative staining transmission electron microscopy.

Results. M1 derived from influenza A/Indonesia/5/05 (H5N1) showed significantly higher expression levels by Coomassie gel staining (FIG. 44, lane 3) compared to VLPs made using B/Florida/4/06 M1 or B/Ann Arbor/1/1986 M1. Also, HA titers of VLPs containing influenza A/Indonesia/5/05 (H5N1) M1, were 4-8 times higher as compared to the other two VLP types. Electron microscopy of VLPs containing influenza A/Indonesia/5/05 (H5N1) M1 had higher concentration of VLP and more regular spherical shape as compared to the other two VLPs (FIG. 45).

Example 37 Making Chimeric VLPs with RSV F1 Protein

Spodoptera frugiperda Sf9 insect cells are maintained and grown as essentially described above. The codon optimized DNA sequences of influenza M1 (SEQ ID NO: 48) and chimeric RSV F1 (HA TM/CY (SEQ ID NO: 80) for expression in insect cells are synthesized and subcloned into pFastBac 1. The result vector expresses both proteins. This vector is used to transform DH10Bac to obtain the bacmid which is transfected into Sf9 cell to obtain the recombinant baculovirus.

Sf9 insect cells are infected for 64 hours at a cell density of 2×10⁶ cells/ml with recombinant baculoviruses that express both chimeric RSV F1 and Indo M1 at a MOI=1. Culture supernatants are harvest by centrifuge at 4000 g. The cell free supernatants are concentrated by ultrafiltration (UF) with a 500 kDa MWCO hollow fiber filter (GE Healthcare). The retentate is buffer exchanged with diafiltration (DF) to 25 mM TrisCl pH 8.0, 300 mM NaCl. The UF/DF retentate is loaded on an ion exchange column (Fractogel TMAE, EMD). VLPs pass through from the column while baculovirus and DNA binds to the column. The flow through fractions containing VLPs are further concentrated with ultrafiltration before loading onto a Sephacryl S500 size exclusion column (GE Healthcare).

The pool of VLPs peak from size exclusion column is analyzed with SDS-PAGE (4-12% Bis-Tris NuPage, Invitrogen) and densitometry for purity. The VLPs are also analyzed with particle size analyzer (Malvern Zetasizer NanoSeries NanoZS), SDS PAGE, western blot analysis, and electron microscopy.

Example 38 Avian Influenza Proteins Comprise an L Domain Sequence Conferring Highly Efficient VLP Production

To identify the key structural elements responsible for the VLP-forming efficiency of avian M1 proteins, the M1 amino acid sequences of three avian influenza strains were aligned with the M1 sequences from a variety of seasonal and pandemic human influenza strains (FIG. 46). The alignments revealed that avian influenza virus strains contain the sequence “YKKL” at amino acids 100-103 of the M1 protein. In contrast, human influenza M1 proteins, which exhibit poor VLP-forming capacity, harbor “YRKL” at amino acids 100-103 of the M1 protein. These four amino acids represent a motif called the late domain (L-domain) which is important in recruiting host components required for budding and release of virus particles.

To evaluate the significance of the YKKL L-domain, site-directed mutagenesis experiments were performed using the human seasonal strain A/Fujian/411/02 containing the YRKL L-domain sequence. FIG. 47 shows the amino acid changes in seven A/Fujian mutants generated by site-directed mutagenesis. Four mutants have only a single point mutation introduced: FJ Mutant 1 (S207N), FJ Mutant 2 (S224N), FJ Mutant 3, (T227A) and FJ Mutant 5 (R101K) and three mutants have combined two, three or four mutations introduced: FJ Mutant 4 (S224N, T227A), FJ Mutant 6 (S207N, S224N, T227A), FJ Mutant 7 (R101K, S207N, S224N, T227A).

Mutants 3 and 7 with an R101K mutation (and thus harboring the avian-like M1 YKKL L-domain sequence) were able to secrete significantly larger amounts of M1 from infected cells compared to strains possessing the seasonal-like M1 YRKL L-domain sequence (FIG. 48). Sf9 cells were infected with recombinant baculovirus expressing different Fujian M1 genes at a multiplicity of infection (MOI) of 1 ffu/cell. Infected sf9 cells and supernatants were harvested at 67 hr post-infection. Infection supernatants were filtered through a 0.45 micron filter and pelleted by centrifugation at 26,000 rpm/min through a 30% sucrose cushion, and resuspended at 50× concentration. Cells and pellets were analyzed by SDS-PAGE, stained for total proteins by Coomassie blue, and stained for influenza M protein by Western blot using an anti-influenza antibody. Lanes 1 to 7 are the intracellular expression of the seven M1 mutants from infected Sf9 cell lysates, lanes 8 to 14 are 50× concentrated 26K pellets of the seven Fujian M1 mutants. Intracellular M1 (28 KDa) of all seven mutants are strongly visible on Coomassie blue stained gel and confirmed by Western blot. Fujian M1 mutant 3 (R101K, lane 10) and mutant 7 (R101K, 5207N, 2224N, T227A, lane 14) are able to release large amounts of M1 particles from infected cells (comparing the bands on the gels, mutant 3 (lanes 3 and 10) and mutant 7 (lanes 7 and 14) show stronger bands in the 30% sucrose pellets than the other mutants, indicating an increased amount of M1 available for association in a VLP, while showing equal amounts of intracellular M1 across all mutants (lanes 1-7). These data demonstrate that mutants harboring the R101K mutation (and thus possessing the avian-like YKKL L-domain) show higher levels of M1 present in the pellet (secreted) fraction than mutants containing the YRKL (seasonal-like) domain.

The role of the avian YKKL L-domain sequence in increased VLP formation was confirmed using co-infection experiments (FIG. 49). Sf9 cells were co-infected with baculovirus expressing A/Fujian hemagglutinin (HA) and neuraminidase (NA), in conjunction with recombinant baculovirus expressing either the avian influenza strain A/Indonesia M1, the wild-type human influenza strain A/Fujian M1, or the “repaired” Fujian M1 mutant, A/Fujian mutant (R101K) which was mutated to mimic the avian YKKL L-domain sequence. As a control, Sf9 cells were infected individually with each recombinant construct in the absence of A/Fujian HA and NA. Infected sf9 cells and supernatants were harvested at 68 hr post-infection, filtered through a 0.45 micron filter and pelleted by ultracentrifugation at 26,000 rpm/min over a 30% sucrose cushion. The resulting pellets were analyzed by SDS-PAGE, stained for total proteins by Coomassie blue, and stained for influenza M1 protein by western blot using anti-A/Fujian/411/03 antibody. Lanes 1 to 7 are the total cell lysates from each culture and lanes 8 to 14 are 50× concentrated 26K supernatant pellets. Each 26K supernatant pellet was assayed for hemagglutination (HA) activity using turkey and guinea pig red blood cells (RBCs) The table shows the HA titer for each VLP sample.

The intracellular levels of A/Indonesia/5/05 M1, wild-type A Fujian/411/02 M1, and A Fujian/411/02 Mutant (R101K) appear to be very similar by Coomassie staining (FIG. 49A). Higher levels of M1 were found in the pellet fraction from strains harboring the YKKL L-domain M1 sequence (see the stronger bands of YKKL-containing A/Indonesia in lanes 8, 11, 14 and YKKL-containing A/Fujian (R101K) in lanes 10 and 13) as compared to the YRKL-containing wild-type A/Fujian strain (see lanes 9 and 12). These results were confirmed with a western immunoblot (see FIG. 49B). The increased intensity of the bands indicate that there is more M1, and thus, more VLPs. Furthermore, strains harboring the YKKL L-domain M1 sequence (A/Indonesia and the repaired A/Fujian mutant (R101K)) showed higher levels of hemagglutination activity than the YRKL-containing wild-type (WT) A/Fujian/411/02 strain using turkey and guinea pig RBCs (table in FIG. 49).

Example 39 Generation of Influenza Reassortant Virus-Like Particles (rVLPs): Residue K¹⁰¹ of M1 Protein Improves rVLP Budding

The present inventors have generated rVLPs, in which the HA and NA proteins were derived from either A/Brisbane/59/07 (H1N1), A/Brisbane/10/07 (H3N2), or B/Florida/4/06 strains, whereas M1 was derived from A/PR/8/34 (H1N1), A/Indonesia/5/05 (H5N1), or from B/Ann Arbor/1/66 virus. The efficiencies of VLP formation for (i) rVLPs containing different M1 proteins, (ii) native VLPs containing the homologous M1 from the same strain as HA and NA, and (iii) M1-deficient VLPs were compared. It was found that the use of M1 protein derived from H5N1 strain improved budding and yields for both influenza type A and type B rVLPs. As described above in example 38, site-directed mutagenesis has shown that budding efficacy was affected by amino acid residue 101 within the M1 protein. The effects of mutations and the role M1 protein in VLP formation are discussed below. These findings clarify the function of M1 and can lead to the improvement of influenza vaccines.

Materials and Methods

Viruses, constructs and cells. Influenza A/Brisbane/59/07 (H1N1), A/Brisbane/10/07 (H3N2), and B/Florida/4/06 viruses grown in Madine-Darby canine kidney (MDCK) were obtained from the Centers for Disease Control and Prevention (CDC, Atlanta, Ga.). Viral RNAs were extracted from each virus using Trizol LS reagent (Invitrogen, Carlsbad, Calif.). RT-PCR was conducted using specific oligonucleotide primers and One-Step RT-PCR system (Invitrogen) to generate cDNA for HA, NA, and M1 genes of 1.7, 1.4, and 0.7 kB in length, respectively, from each virus. For A/Brisbane/59/07 (H1N1), the HA and NA primers were designed according to GenBank ISDN282676 and ISDN285099 sequences, respectively. For A/Brisbane/10/07 (H3N2), the HA and NA primers were according to GenBank EU199366 and EU199420, respectively. For both viruses, the M1 genes were generated by using forward and reverse primers: 5′-ATGagtcttttaaccgaggtcgaa-3′ and: 5′-TCActtgaatcgttgcatctgcac-3′ (start and stop codons are capitalized). For B/Florida/4/06, the HA and NA primers were generated according to GenBank ISDN285778 and ISDN261650, respectively, whereas M1 gene was generated using primers 5′-ATGtcgctgtttggagacacaattgcctacc-3′ and 5′-TTAtagatatttcttcacaagagctgaat-3′. For reassortant VLPs, the M1 genes of A/PR/8/34 (H1N1, GenBank AF389121), A/Udorn/72 (H3N2, GenBank CY009637), A/Indonesia/5/05 (H5N1, GenBank CY014173), and B/Ann Arbor/1/66 (GenBank M20176) were synthesized at GeneArt AG (Regensburg, Germany). Similarly, A/Fujian/411/02 (H3N2) HA, NA, and M1 genes were synthesized at GeneArt. Site-directed mutagenesis of M1 genes was carried out using QuikChange site-directed mutagenesis kit (Stratagene, La Jolla, Calif.).

The HA, NA, or M1 genes were cloned into a pFastBac1 baculovirus transfer vector downstream of the AcMNPV polyhedrin promoter between BamHI-HindIII sites. Genes were combined within a pFastBac1-based transfer vector in a tandem fashion as described previously (Pushko et al., 2005).

Spodoptera frugiperda Sf9 insect cells (ATCC CRL-1711) were maintained as suspension cultures in HyQ-SFX insect serum free medium (HyClone, Logan, Utah) at 27±2° C. Recombinant baculoviruses (rBVs) expressing influenza genes were generated using a Bac-to-Bac baculovirus expression system (Invitrogen). Briefly, rBV bacmid DNAs were generated by site-specific homologous recombination following transformation of pFastBac1-based transfer plasmids containing influenza genes into E. coli DH10Bac competent cells (Invitrogen), which contained the AcMNPV baculovirus genome. The recombinant bacmid DNA was extracted from E. coli cells and transfected into Sf9 cells using CellFectin reagent (Invitrogen). The rBVs were recovered, plaque-purified, amplified, and the titers of rBV stocks were determined by using BacPak Baculovirus Rapid Titer Kit (Clontech, Mountain View, Calif.) or by agarose plaque assay using Sf9 cell monolayers.

Purification and detection of influenza VLPs. For purification of VLPs, Sf9 cells were infected at a multiplicity of infection (MOI) of 3.0 for 66-72 hr at a cell density of 2×10⁶ cells/ml with rBVs encoding influenza proteins. VLPs were concentrated and partially purified from the Sf9 media by ultracentrifugation at 100 000×g for 1 hr through a 30% sucrose cushion and resuspended in phosphate buffered saline (PBS), pH7.2. Alternatively, SF9 culture supernatants containing VLPs were concentrated by tangential flow filtration with a 500,000 molecular weight hollow fiber filter (GE HealthCare), and the purification of influenza VLPs was carried out using a combination of gel filtration and ion exchange chromatography.

Influenza proteins were analyzed by SDS-PAGE using 4-12% gradient polyacrylamide gels (Invitrogen), and stained with GelCode Blue Stain reagent (Pierce, Rockford, Ill.) and quantified by scanning densitometry using OneDscan system (BD Biosciences, Rockville, Md.). Western blot was carried out using antisera specific for influenza viruses. After electrophoretic protein transfer, membranes were blocked for 1 hr at 25° C. in blocking solution (Invitrogen), rinsed 3 times (5 min each) with PBS, pH7.2, and incubated for 16 hr with indicated influenza protein-specific antisera at 1:1,000 dilution. Following PBS rinsing step as indicated above, membranes were incubated at 25° C. for 1 hr with alkaline phosphatase conjugated goat IgG (H+L) secondary antibodies. Membranes were rinsed again with PBS, pH7.2 as indicated above, and protein bands were developed using the one-component BCIP/NBT phosphatase substrate (Kirkegaard and Perry, Gaithersburg, Md.).

Hemagglutination and neuraminidase enzyme activity assays. Serial dilutions of VLPs were prepared in 96-well microtiter plates, followed by the addition of 1.5% guinea pig or 1% turkey red blood cells (RBC) (Lampire Biologicals, Pipersville, Pa.) in PBS. RBC were stored at 4° C. and used within 72 hours of preparation. The plates were mixed by agitation, covered, the RBCs were allowed to settle for 30-60 min at room temperature, and the HA titer was determined by visual inspection.

For NA enzyme activity essay, VLP samples (25 μl) were transferred to a black 96-well plate and 75 μl of 20 μM methyl-umbelliferyl-N-acetyl neuraminic acid was added. After incubation of the plate at 37° C. for 1 hr, 100 μl stop solution (0.1 M glycine, pH 10.7-25% ethanol) was added to each well and fluorescence was read on a fluorometer (Turner BioSystems, Sunnyvale, Calif.) with excitation and emission filters of 365 nm and 450 nm, respectively.

Negative staining electron microscopy. VLP samples were adsorbed by flotation for 2 min onto a freshly discharged 400 mesh carbon parlodion-coated copper grid (PolySciences, Warrington, Pa.). The grid was rinsed with buffer containing 20 mM Tris, pH 7.4, and 120 mM KCl and negatively stained with 1% phosphotungstic acid, then dried by aspiration. VLPs were visualized on a Hitachi H-7600 transmission electron microscope (Hitachi High Technologies America, Schaumburg, Ill.) operating at 80 kV and digitally captured with a CCD camera at 1K×1K resolution (Advanced Microscopy Techniques Corp., Danvers, Mass.).

Results

Constructs for expression of native, reassortant, and M1-deficient VLPs. The rBV constructs for expression of A/Brisbane/59/07 (H1N1), A/Brisbane/10/07 (H3N2), and B/Florida/4/06 VLPs are shown on FIG. 50. These three strains were recommended by WHO/CDC for 2008-09 influenza season vaccine development (FDA, 2008). Influenza HA, NA, and M1 cDNA genes were generated from each strain by RT-PCR using extracted viral RNAs as templates. The HA, NA, and M1 genes were combined within an rBV in a tandem fashion so that each gene was expressed from its own expression cassette that included polyhedrin promoter and SV40 polyadenylation signal. For generation of native (wild type) VLPs, the M1, HA, and NA genes were derived from the same virus. In the reassortant VLPs (rVLPs), the HA and NA genes were derived from the same virus, whereas M1 gene was derived from either A/Indonesia/5/05 (H5N1), A/PR/8/34 (H1N1), or B/Ann Arbor/1/66 viruses (FIG. 50). Thus, M1 from A/PR/8/34 has been used to generate A/Brisbane/59/07 (H1N1) and A/Brisbane/10/07 (H3N2) rVLPs, whereas M1 protein from B/Ann Arbor/1/66 has been used to generate B/Florida/4/06 rVLPs. The M1 from A/Indonesia/5/05 has been used to generate rVLPs for all three seasonal influenza strains including B/Florida/4/06 (FIG. 1). In summary, for each influenza strain, a native as well as two rVLP constructs have been made. In addition, for each strain, we have made the M1-deficient construct that expressed the HA and NA proteins only, with no M1 protein (FIG. 50). The rBVs expressing native, reassortant, and M1-deficient VLPs were prepared using homologous recombination with baculovirus genome in E. coli DH10Bac cells followed by transformation into Sf9 cells, as described in the Materials and Methods.

Expression of native, reassortant and M1-deficient VLPs. Sf9 cells were infected with rBVs, which contained gene cassettes for expression of native, reassortant, and M1-deficient VLPs for N1N1, H3N2, and influenza B strains (FIG. 50). After incubation for 72 hr, VLPs from the media were concentrated and partially purified by ultracentrifugation. Expression of influenza proteins in VLPs was determined by SDS-PAGE and western blot (FIG. 51), as well as by hemagglutination and NA enzyme activity assays (Table 7).

TABLE 7 Expression and Functional Activity of Native, Reassortant, and M1-deficient VLPs derived from 2008-2009 influenza vaccine strains. Total Protein, NA activity, VLP M1 Source rBV* mg/ml HA Titer** mU/ml A/Brisbane/59/07 (H1N1) Native A/Brisbane/59/07 (H1N1) 526 0.91 ± 0.02 16 384  702.7 ± 18.9 Reassortant A/Indonesia/5/05 (H5N1) 599 1.07 ± 0.01 65 536 1 223.1 ± 46.6  Reassortant A/PR/8/34 (H1N1) 587 1.11 ± 0.03 16 384 1 142.2 ± 26.6  M1-deficient — 590 0.69 ± 0.01   128  477.9 ± 24.2 A/Brisbane/10/07 (H3N2) Native A/Brisbane/10/07 (H3N2) 528 0.73 ± 0.02 16 384 545.7 ± 9.2 Reassortant A/Indonesia/5/05 (H5N1) 520 0.86 ± 0.00 65 536 950.2 ± 7.6 Reassortant A/PR/8/34 (H1N1) 521 0.69 ± 0.02 32 768 877.0 ± 9.1 M1-deficient — 547 0.49 ± 0.01  4 096  376.6 ± 18.3 B/Florida/4/06 Native B/Florida/4/06 540 0.92 ± 0.01 32 768 249.5 ± 0.0 Reassortant A/Indonesia/5/05 (H5N1) 538 0.88 ± 0.01 262 144  696.5 ± 9.3 Reassortant B/Ann Arbor/1/66 539 0.83 ± 0.01 32 768 397.2 ± 1.3 M1-deficient — 601 0.85 ± 0.04 32 768 160.9 ± 4.8 *The rBV designations are according to FIG. 50. **HA titers were determined using guinea pig red blood cells.

Expression of HA and NA was detected in all native, reassortant, and M1-deficient VLP preparations derived from the three strains (FIG. 51). By SDS-PAGE and western blot, the rVLPs contained the HA and NA proteins at the levels equivalent or greater to those of the native VLPs or M1-deficient VLPs. Consistent with previous observations (Pushko et al., 2005), the HA was expressed in Sf9 cells as HA0 polypeptide of 65-74 kDa, with no significant cleavage into HA1 and HA2 detected. The NA was found as a polypeptide of approximately 50 kDa. As expected, the M1 band of approximately 26 kDa was observed in the native VLPs and in rVLPs, but not in M1-deficient VLPs (FIG. 51, lanes 4, 8, 12). The levels of expression of M1 in the VLPs varied, with the highest expression observed in rVLPs that contained the A/Indonesia/5/05 (H5N1) M1 (FIG. 51, lanes 2, 6, 10). Interestingly, intracellular levels of M1 proteins including A/Indonesia/5/05 M1 were comparable in Sf9 cells (FIG. 51, lines 1-7, bottom panel). Surprisingly, significant amounts of A/Indonesia/5/05 M1 were also detected in B/Florida/4 VLPs (lane 10), suggesting effective formation of the heterotypic rVLPs. In all rVLP preparations containing A/Indonesia/5/05 M1, a prominent protein band with apparent molecular weight of 52 kDa was also detected, which corresponded to the predicted molecular weight of a dimeric M1. The presence of M1 protein in this band was confirmed by liquid chromatography/mass spectrometry method (data not shown).

The expression levels of M1 correlated with the expression levels and functional activity of HA and NA. In all three strains, the lowest levels of HA and NA proteins were detected in M1-deficient VLP preparations (FIG. 51, lanes 4, 8, 12), indicating that the absence of M1 protein adversely affected generation of VLPs. In order to assess the levels of HA and NA quantitatively, hemagglutination and neuraminidase activity assays were conducted. The highest HA and NA titers were observed in rVLPs containing A/Indonesia/5/05 M1, whereas the lowest titers were detected in M1-deficient VLPs (Table 7).

Purification and electron microscopy of native, reassortant and M1-deficient VLPs. In the next experiment, the rVLPs were purified using a gel filtration and ion exchange chromatography. By using this method, the majority of contaminants including rBV were removed. The HA, NA, and M1 co-purified during the process confirming that these proteins are associated into rVLPs. The example of purified rVLPs, as well as of native and M1-deficient H3N2 VLPs is shown on FIG. 52. Similarly to the previous results (Table 7), the levels of HA and NA activity in the purified VLPs correlated with the M1 content (Table 8).

TABLE 8 Hemagglutinin and Neuraminidase Enzyme Activity of Purified A/Brisbane/10/07 (H3N2) VLPs. HA NA activity, H3N2 VLP M1 Source rBV* M1, %** Titer*** mU/ml Native A/Brisbane/ 528 19.3 ± 0.6 512  4 941 59/2007 (H1N1) Reassortant A/Indonesia/ 521 38.1 ± 0.2 1 024   18 002.6 5/05 (H5N1) Reassortant A/PR/8/34 520 40.1 ± 0.6 512 16 290.1 (H1N1) M1-deficient — 547 NA 216  4 325.8 *The rBV designations are according to FIG. 50. **M1 content determined by SDS-PAGE followed by scanning densitometry. ***HA titers were dtermined using guinea pig red blood cells.

The highest HA and NA activity was observed in rVLPs containing A/Indonesia/5/05 M1, whereas the lowest activity was observed in M1-deficient VLPs. The band corresponding to the dimeric form of M1 was apparent in the rVLPs containing M1 derived from A/Indonesia/5/05 (H5N1) virus.

Ultrastructure of VLPs was analyzed by negative staining transmission electron microscopy (FIG. 52B). Influenza-like pleomorphic particles with diameter of approximately 100 nm were detected in all four H3N2 VLPs including rVLPs and M1-deficient VLPs. In spite of the differences in the levels of expression of M1 (FIG. 51, 52A), no significant amounts of M1-only VLPs were detected. Most of the M1-deficient VLPs had electron-dense inner areas, possibly reflecting the enhanced infiltration of stain inside the “empty” M1-deficient particles. In the M1-deficient VLPs, particles were also observed, which contained core structures surrounded by influenza-like envelope with characteristic spikes of HA (FIG. 52B, panel 4). It is believed that the absence of M1 in the M1-deficient VLPs may have lead to incorporation of unrelated proteins derived from Sf9 cells or baculovirus, into VLPs in place of the M1 protein.

K¹⁰¹ residue within M1 protein is important for budding of M1 particles. The data suggested that the presence of M1 derived from A/Indonesia/5/05 (H5N1) virus correlated with the improved budding of rVLPs (Tables 7, 8). In order to elucidate amino acid residues within the M1 that affected budding, site-directed mutagenesis of M1 was conducted. It has been reported previously that M1 alone can form particles released into the medium (Gomez-Puertas et al., 2000). This provides a convenient assay for determination of the effect of mutations. In the first set of experiments, A/Fujian/411/02 M1 was mutated. Out of eighteen amino acid differences between the M1 proteins of A/Fujian/411/02 and A/Indonesia/5/05, R¹⁰¹, S²⁰⁷, S²²⁴, or T²²⁷ were altered in A/Fujian/411/02 to corresponding residues K¹⁰¹, N²⁰⁷, N²²⁴, or A²²⁷ of A/Indonesia/5/05 M1. Residues at these positions are not conserved among different strains and may affect M1 polypeptide folding, according to computer predictions (data not shown). Individual mutations or combinations of these mutations were made, rBVs generated, and expression of mutant M1 proteins was determined in Sf9 cells (FIG. 53A, lanes 1-7), as well as in the media (FIG. 53A, lanes 8-14). All mutants were expressed at equivalent levels in the cells. However, the only proteins that were detected at high levels in the media were A/Fujian/411/02 M1 containing K¹⁰¹, as well as quadruple mutant containing K¹⁰¹, N²⁰⁷, N²²⁴, and A²²⁷ residues derived from A/Indonesia/5/05 M1 (FIG. 53A, lanes 10 and 14). This result suggests the importance of K¹⁰¹ residue for budding of M1-only VLPs.

In order to confirm the role of K¹⁰¹ on budding of M1, residue 101 was mutated within the M1 genes of A/Indonesia/5/05 (H5N1) and A/Udorn/72 (H3N2) and the effects of mutations on budding of M1-only particles was determined (FIG. 53B). According to X-ray crystallography of the N-terminal portion of M1 (Arzt et al., 2001), the amino acid residue 101 is located within the sixth α-helix of M1 (FIG. 54A) and may be involved in the intramolecular interactions between the M1 subunits (Harris et al., 2001). Alternatively, residue K¹⁰¹ can be a part of nuclear localization sequence 101-RKLKR-105 (Ye et al., 1995) or a part of YXXL-type late (L) domain spanning residues 100-103. In the human influenza A isolates A/PR/8/34, A/Udorn/72, A/Fujian/411/02, and 2008-09 influenza A vaccine strains, residue 101 corresponds to R¹⁰¹, whereas avian isolates including A/Indonesia/5/05 (H5N1) have K¹⁰¹ at this position (FIG. 54B).

In order to elucidate if R/K¹⁰¹ residue affects budding of M1-only particles, two mutations were made: the K¹⁰¹ in A/Indonesia/5/05 was changed to R¹⁰¹, whereas R¹⁰¹ in A/Udorn/72 was changed to K¹⁰¹. Corresponding rBVs that encoded the wild type and mutant M1 proteins of A/Indonesia/5/05 and A/Udorn/72 were constructed and used to infect Sf9 cells. The expression of M1 was analyzed in infected Sf9 cells and media by SDS-PAGE and western blot. All four M1 proteins were expressed at similar levels within the Sf9 cells (FIG. 53B, lanes 1-4). Efficient release of M1 particles of A/Indonesia/5/05 wild type M1-K¹⁰¹ was detected in the medium, suggesting effective budding from the cells (lane 5). However, when K¹⁰¹ in Indonesia/5/05 was changed to R¹⁰¹, budding was suppressed approximately 4-fold, according to stained SDS-PAGE gel (lane 6) and densitometry analysis. Likewise, the wild type M1 of A/Udorn/72 had low budding efficacy (lane 7), but when R¹⁰¹ in the wild type A/Udorn/72 M1 was changed to K¹⁰¹, budding improved 4-fold (lane 8) confirming the role of K¹⁰¹ in budding.

Engineered M1 protein with K¹⁰¹ residue improves budding of influenza rVLPs. The data showed that K¹⁰¹ residue affects budding of M1-only particles. The present inventors further evaluated if the introduction of K¹⁰¹ in place of R¹⁰¹ can also improve budding of VLPs comprised of HA, NA, and M1 proteins. For this purpose, the present inventors constructed rBV that co-expressed A/Fujian/411/02 (H3N2) HA and NA, as well as two rBVs encoding either the wild type A/Fujian/411/02 M1 containing R¹⁰¹, or the mutant M1 containing K¹⁰¹ (FIG. 55A). The M1 proteins were expressed in Sf9 cells either alone, or they were co-expressed along with A/Fujian/411/02 HA and NA proteins following co-infection with two rBVs. As a control, we used rBV that expressed A/Indonesia/5/05 M1 protein. Infected cells and media were evaluated for the expression of influenza proteins.

When expressed alone or co-expressed along with HA and NA, intracellular expression of the A/Fujian/411/02 wild type M1-R¹⁰¹ (FIG. 55B, lanes 2, 5) was equivalent to expression of A/Indonesia/5/05 M1-K¹⁰¹ (lanes 1, 4) or mutant A/Fujian/411/02 M1-K¹⁰¹ (lanes 3, 6). However, release of A/Fujian/411/02 wild type M1-R¹⁰¹ into the medium from infected Sf9 cells (lanes 8, 12) was reduced up to 12 times compared to mutant M1-K¹⁰¹ (lanes 9, 12) or A/Indonesia/5/05 M1-K¹⁰¹ (lanes 7, 10). Budding efficacy of M1-only particles correlated with that of the VLPs. Thus, a single K¹⁰¹ mutation improved budding of VLPs containing A/Fujian/411/02 M1 to the levels similar to rVLPs containing A/Indonesia/5/05 M1.

In order to confirm the improved budding of the VLPs containing engineered A/Fujian/411/02 M1-K¹⁰¹ protein, hemagglutination and NA enzyme activity assays were carried out on the VLP preparations (Table 9).

TABLE 9 Effect of K¹⁰¹ Mutation in the M1 Protein on Budding of A/Fujian/411/02 (H3N2) VLPs H3N2 VLP M1 Source rBV* Residue 101 HA Titer** Native A/Fujian/411/02 230 R¹⁰¹   512 (H3N2) Native, K¹⁰¹ A/Fujian/411/02 561 K¹⁰¹ 2 048 with K¹⁰¹ Reassortant A/Indonesia/5/05 299 K¹⁰¹ 2 048 (H5N1) *The rBV designations are according to FIG. 50. **HA titers were determined using guinea pig red blood cells.

In these assays, VLPs that contained A/Indonesia/5/05 M1-K¹⁰¹ or A/Fujian/411/02 M1-K¹⁰¹ proteins demonstrated 4-fold improvement of HA titers and 2-fold improvement of the NA enzyme activity titers, as compared to A/Fujian/411/02 wild type M1-R¹⁰¹. These results have shown that engineering of M1 by introduction of a single R¹⁰¹K mutation improves budding and the yields of influenza VLPs.

Conclusions

In this Example, the present inventors provide evidence that trivalent rVLP-based vaccine can be efficiently made for all three 2008-09 influenza strains, including influenza B, by using a single high-yield influenza M1 protein, such as A/Indonesia/5/05 (H5N1). The efficient generation of heterotypic A/B VLPs comprised of type A M1 and type B HA and NA proteins is somewhat unexpected. Phenotypic mixing of proteins from different enveloped viruses has been previously described, for example between SV5, a paramyxovirus, and vesicular stomatitis virus, a rhabdovirus (Choppin et al., 1970). However, phenotypic mixing of influenza A and B viruses is less studied. In the currently licensed vaccines, different donor strains are used for type A and type B vaccines, such as A/PR/8/34 (H1N1) or B/Ann Arbor/1/66 (Chen et al., 2008).

The data presented herein shows that M1 proteins derived from various strains had varying capabilities for budding, which in turn affected budding of VLPs from Sf9 cells. Among rVLPs, the highest yields were observed when VLPs were made in the presence of A/Indonesia/5/05 (H5N1) M1 protein. The present inventors found that the K¹⁰¹ residue, characteristic for M1 of avian influenza viruses, improves budding of seasonal strains of VLPs if introduced in the M1 protein. Although reasons for improvement of budding are not clear, it is believed that the K¹⁰¹ residue represents the “molecular switch” that triggers formation of stable M1 dimers. Indeed, a major band corresponding to a dimeric M1 was consistently detected in rVLP preparations that contained A/Indonesia/5/05 M1-K¹⁰¹, but not A/PR/8/34 M1-R¹⁰¹ or B/Florida/4/06 M1 (FIG. 51, 52). Formation of stable dimers between the M1 subunits may stabilize M1 lattice and result in improved stability and budding of VLPs. However, additional viral or/and cellular factors may also contribute to the formation of VLPs. For example, K¹⁰¹ residue, which is located within 100-YKKL-103 sequence of A/Indonesia/5/05 M1 protein may be the part of an YXXL-type viral L-domain that could facilitate budding. In other viruses, such as retroviruses, the L-domains recruit host proteins that are necessary for budding and release of virus particles (Demirov and Freed, 2004). Another possibility is that K¹⁰¹ interferes with nuclear localization sequence 101-RKLKR-105, which may affect intracellular distribution of M1 (Ye et al., 1995).

The results reported here can be useful for the development of other influenza vaccine approaches, for example for co-expression of influenza genes from DNA constructs or from viral vectors, as well as for manufacturing of current influenza vaccines.

The following references are incorporated herein by reference:

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Other Embodiments

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims provided herein. 

1. A virus-like particle (VLP) comprising an influenza M1 protein, wherein said M1 protein comprises the amino acid residues YKKL at the positions corresponding to positions 100-103 of SEQ ID NO:
 49. 2. The VLP of claim 1, wherein said influenza M1 protein is derived from an avian influenza virus strain.
 3. The VLP of claim 2, wherein said avian influenza virus strain is A/Indonesia/5/05.
 4. The VLP of claim 1, wherein said VLP further comprises an influenza hemagglutinin (HA) and/or a neuraminidase (NA) protein.
 5. The VLP of claim 4, wherein said HA and NA proteins are derived from an avian influenza virus.
 6. The VLP of claim 5, wherein said avian influenza virus is H5N1.
 7. The VLP of claim 5, wherein said avian influenza virus is H9N2.
 8. The VLP of claim 4, wherein said HA and NA proteins are derived from a seasonal influenza virus.
 9. The VLP of claim 8, wherein said seasonal influenza virus is a type A influenza virus.
 10. The VLP of claim 8, wherein said seasonal influenza virus is a type B influenza virus.
 11. The VLP of claim 4, wherein said HA and/or NA exhibit hemagglutinin activity and/or neuraminidase activity, respectively.
 12. The VLP of claim 4, wherein said HA and/or NA are chimeric proteins.
 13. The VLP of claim 12, wherein said chimeric proteins comprise external domains of non-avian influenza HA and/or NA protein sequences fused to the transmembrane and/or cytoplasmic terminal domains of the avian HA and/or NA.
 14. The VLP of claim 13, wherein said non-avian influenza HA and/or NA are from influenza strain A/Wisconsin/67/2005 and said avian influenza HA and/or NA are from influenza strain A/Indonesia/5/05.
 15. A method of increasing the efficiency of VLP production comprising expressing an influenza M1 protein in a host cell, wherein said M1 protein comprises the amino acid residues YKKL at the positions corresponding to positions 100-103 of SEQ ID NO:
 49. 16. The method of claim 15, wherein said influenza M1 protein is derived from an avian influenza virus strain.
 17. The method of claim 16, wherein said avian influenza virus strain is A/Indonesia/5/05.
 18. The method of claim 15, wherein said VLP further comprises an influenza hemagglutinin (HA) and/or a neuraminidase (NA) protein.
 19. The VLP of claim 18, wherein said HA and NA proteins are derived from a seasonal influenza virus.
 20. A vaccine comprising the VLP of claim
 1. 